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Номер 819, страница 225 - гдз по алгебре 9 класс учебник Солтан, Солтан
Авторы: Солтан Г. Н., Солтан А. Е., Жумадилова А. Ж.
Тип: Учебник
Издательство: Кокшетау
Год издания: 2019 - 2026
ISBN: 978-601-317-424-2
Рекомендовано Министерством образования и науки Республики Казахстан
Популярные ГДЗ в 9 классе
IV. Тригонометрия. 30. Упражнения на повторение раздела «Тригонометрия» - номер 819, страница 225.
App\Models\Task {#1024 // resources/views/models/task/default.blade.php #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108565 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => "226" "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-819" "field_display_title" => "819" "field_outside_task" => "0" "field_task_type" => Illuminate\Database\Eloquent\Collection {#331 #items: array:1 [ 0 => App\Models\Term {#1029 #connection: "mysql" #table: "terms" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:6 [ "id" => 26 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "name" => "номер" "field_cases" => array:6 [ "field_accusative_case" => "номер" "field_creative_case" => "номером" "field_dative_case" => "номеру" "field_genitive_case" => "номера" "field_nominative_case" => "номер" "field_prepositional_case" => "номере" ] "field_short_name" => "№" ] #original: array:6 [ "id" => 26 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "name" => "номер" "field_cases" => array:6 [ "field_accusative_case" => "номер" "field_creative_case" => "номером" "field_dative_case" => "номеру" "field_genitive_case" => "номера" "field_nominative_case" => "номер" "field_prepositional_case" => "номере" ] "field_short_name" => "№" ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1026 #items: [] #escapeWhenCastingToString: false } "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#342 #items: array:1 [ 0 => App\Models\Branch {#1023 #connection: "mysql" #table: "branches" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1107662 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "IV. Тригонометрия" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#333 #items: [] #escapeWhenCastingToString: false } "field_page_start" => "147" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1033 #items: array:1 [ 0 => App\Models\Book {#1030 #connection: "mysql" #table: "books" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1032 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1035 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1037 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1039 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1043 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1044 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1046 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1048 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1050 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1051 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1052 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1053 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1054 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1055 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1056 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1057 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1058 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1059 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #original: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1032 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1035 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1037 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1039 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1043 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1044 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1046 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1048 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1050 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1051 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1052 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1053 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1054 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1055 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1056 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1057 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1058 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1059 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "branch_parent" => Illuminate\Database\Eloquent\Collection {#1060 #items: [] #escapeWhenCastingToString: false } ] #original: array:24 [ "id" => 1107662 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "IV. Тригонометрия" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#333} "field_page_start" => "147" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1033} "branch_parent" => Illuminate\Database\Eloquent\Collection {#1060} ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "parent_branches" => Illuminate\Database\Eloquent\Collection {#1061 #items: array:2 [ 0 => App\Models\Branch {#1023} 1 => App\Models\Branch {#1062 #connection: "mysql" #table: "branches" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1107672 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "30. Упражнения на повторение раздела «Тригонометрия»" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1063 #items: [] #escapeWhenCastingToString: false } "field_page_start" => "221" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1064 #items: array:1 [ 0 => App\Models\Book {#1065 #connection: "mysql" #table: "books" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1066 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1068 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1070 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1072 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1076 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1077 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1079 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1081 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1083 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1084 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1085 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1086 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1087 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1088 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1089 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1090 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1091 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1092 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #original: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1066 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1068 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1070 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1072 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1076 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1077 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1079 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1081 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1083 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1084 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1085 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1086 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1087 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1088 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1089 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1090 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1091 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1092 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "branch_parent" => Illuminate\Database\Eloquent\Collection {#1093 #items: array:1 [ 0 => App\Models\Branch {#1094 #connection: "mysql" #table: "branches" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1107662 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "IV. Тригонометрия" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1095 …2} "field_page_start" => "147" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1096 …2} "branch_parent" => Illuminate\Database\Eloquent\Collection {#1125 …2} ] #original: array:24 [ "id" => 1107662 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "IV. Тригонометрия" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1095 …2} "field_page_start" => "147" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1096 …2} "branch_parent" => Illuminate\Database\Eloquent\Collection {#1125 …2} ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } ] #original: array:24 [ "id" => 1107672 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_display_title" => "30. Упражнения на повторение раздела «Тригонометрия»" "field_branch_order" => null "field_url" => null "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1063} "field_page_start" => "221" "field_branch_display" => "0" "field_branch_expanded" => "0" "field_display_branch_in_title" => "1" "field_display_task_interval" => "0" "field_display_branch_page" => "1" "field_branch_title_in_content" => "0" "field_navigation_title" => null "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_branch_cover" => [] "field_branch_covers" => [] "book" => Illuminate\Database\Eloquent\Collection {#1064} "branch_parent" => Illuminate\Database\Eloquent\Collection {#1093} ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "content" => Illuminate\Database\Eloquent\Collection {#1126 #items: array:3 [ 0 => App\Models\Element {#1127 #connection: "mysql" #table: "elements" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:7 [ "id" => 1277174 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1128 #items: array:1 [ 0 => App\Models\Edition {#1129 #connection: "mysql" #table: "editions" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:21 [ "id" => 4953 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Условие" "field_order" => "1" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1130 …2} "field_content_type" => "free" "field_content_mode" => "text, image" "field_page_content_mode" => "image" "field_content_text_checked" => null "field_page_content_text_checked" => "0" "field_solution_author" => "Автор" "field_moderator" => "pasha" "field_edition_type" => "statement" "field_root_dir" => "0-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1132 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1133 …2} "field_process_formula" => "katex" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1134 …2} "field_content_source" => null ] #original: array:21 [ "id" => 4953 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Условие" "field_order" => "1" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1130 …2} "field_content_type" => "free" "field_content_mode" => "text, image" "field_page_content_mode" => "image" "field_content_text_checked" => null "field_page_content_text_checked" => "0" "field_solution_author" => "Автор" "field_moderator" => "pasha" "field_edition_type" => "statement" "field_root_dir" => "0-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1132 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1133 …2} "field_process_formula" => "katex" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1134 …2} "field_content_source" => null ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "text" => "<p><strong>819.</strong> Алихан получил задание: упростить выражение</p><p>$\sin^2 \frac{\alpha - \beta}{2} + \sin^2 \frac{\alpha + \beta}{2} - 2\sin \frac{\alpha + \beta}{2} \cdot \sin \frac{\alpha - \beta}{2} \cdot \cos \beta.$ Он провел следующие преобразования этого выражения:</p><p>$\frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} - (\cos \alpha + \cos \beta) \cdot \cos \beta =$</p><p>$= 1 - \frac{\cos(\alpha - \beta) + \cos(\alpha + \beta)}{2} - \cos \alpha \cdot \cos \beta - \cos^2\beta =$</p><p>$= 1 - \cos \alpha \cdot \cos \beta - \cos \alpha \cdot \cos \beta - \cos^2\beta = \sin^2\beta - 2\cos \alpha \cdot \cos \beta.$</p><p>Софии было поручено проверить, получил ли Алихан правильный ответ. Она вместо $\alpha$ и $\beta$ подставила в исходное и последнее выражение $0$ и получила неверное равенство $0 = -2.$</p><p>Следовательно, ответ неправильный. Найдите ошибку в преобразованиях Алихана и выполните задание правильно.</p>" "img" => array:2 [ 0 => array:5 [ "name" => "819-1.jpg" "alt" => null "width" => "1581" "height" => 848 "path" => "/media/algebra_09/soltan-u19/0-1/819-1.webp?ts=1752834807" ] 1 => array:5 [ "name" => "819-2.jpg" "alt" => null "width" => "1472" "height" => 222 "path" => "/media/algebra_09/soltan-u19/0-1/819-2.webp?ts=1752834807" ] ] ] #original: array:7 [ "id" => 1277174 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1128} "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "text" => "<p><strong>819.</strong> Алихан получил задание: упростить выражение</p><p>$\sin^2 \frac{\alpha - \beta}{2} + \sin^2 \frac{\alpha + \beta}{2} - 2\sin \frac{\alpha + \beta}{2} \cdot \sin \frac{\alpha - \beta}{2} \cdot \cos \beta.$ Он провел следующие преобразования этого выражения:</p><p>$\frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} - (\cos \alpha + \cos \beta) \cdot \cos \beta =$</p><p>$= 1 - \frac{\cos(\alpha - \beta) + \cos(\alpha + \beta)}{2} - \cos \alpha \cdot \cos \beta - \cos^2\beta =$</p><p>$= 1 - \cos \alpha \cdot \cos \beta - \cos \alpha \cdot \cos \beta - \cos^2\beta = \sin^2\beta - 2\cos \alpha \cdot \cos \beta.$</p><p>Софии было поручено проверить, получил ли Алихан правильный ответ. Она вместо $\alpha$ и $\beta$ подставила в исходное и последнее выражение $0$ и получила неверное равенство $0 = -2.$</p><p>Следовательно, ответ неправильный. Найдите ошибку в преобразованиях Алихана и выполните задание правильно.</p>" "img" => array:2 [ 0 => array:5 [ "name" => "819-1.jpg" "alt" => null "width" => "1581" "height" => 848 "path" => "/media/algebra_09/soltan-u19/0-1/819-1.webp?ts=1752834807" ] 1 => array:5 [ "name" => "819-2.jpg" "alt" => null "width" => "1472" "height" => 222 "path" => "/media/algebra_09/soltan-u19/0-1/819-2.webp?ts=1752834807" ] ] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 1 => App\Models\Element {#1135 #connection: "mysql" #table: "elements" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:6 [ "id" => 1278465 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1136 #items: array:1 [ 0 => App\Models\Edition {#1137 #connection: "mysql" #table: "editions" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:21 [ "id" => 4954 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Решение" "field_order" => "2" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1138 …2} "field_content_type" => "free" "field_content_mode" => "image" "field_page_content_mode" => "" "field_content_text_checked" => "0" "field_page_content_text_checked" => "0" "field_solution_author" => "Неизвестный" "field_moderator" => "pasha" "field_edition_type" => "solution" "field_root_dir" => "1-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1140 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1141 …2} "field_process_formula" => "" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1142 …2} "field_content_source" => null ] #original: array:21 [ "id" => 4954 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Решение" "field_order" => "2" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1138 …2} "field_content_type" => "free" "field_content_mode" => "image" "field_page_content_mode" => "" "field_content_text_checked" => "0" "field_page_content_text_checked" => "0" "field_solution_author" => "Неизвестный" "field_moderator" => "pasha" "field_edition_type" => "solution" "field_root_dir" => "1-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1140 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1141 …2} "field_process_formula" => "" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1142 …2} "field_content_source" => null ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "img" => array:1 [ 0 => array:5 [ "name" => "819-1.jpg" "alt" => null "width" => "1412" "height" => 958 "path" => "/media/algebra_09/soltan-u19/1-1/819-1.webp?ts=1752831631" ] ] ] #original: array:6 [ "id" => 1278465 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1136} "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "img" => array:1 [ 0 => array:5 [ "name" => "819-1.jpg" "alt" => null "width" => "1412" "height" => 958 "path" => "/media/algebra_09/soltan-u19/1-1/819-1.webp?ts=1752831631" ] ] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 2 => App\Models\Element {#1143 #connection: "mysql" #table: "elements" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:6 [ "id" => 1554420 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1144 #items: array:1 [ 0 => App\Models\Edition {#1145 #connection: "mysql" #table: "editions" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:21 [ "id" => 5665 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Решение 2 (rus)" "field_order" => "3" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1146 …2} "field_content_type" => "free" "field_content_mode" => "text" "field_page_content_mode" => "" "field_content_text_checked" => null "field_page_content_text_checked" => "0" "field_solution_author" => "Gemini 2.5 Pro" "field_moderator" => "tolik" "field_edition_type" => "solution" "field_root_dir" => "2-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1148 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1149 …2} "field_process_formula" => "katex" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1150 …2} "field_content_source" => null ] #original: array:21 [ "id" => 5665 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "title" => "Решение 2 (rus)" "field_order" => "3" "field_publisher" => Illuminate\Database\Eloquent\Collection {#1146 …2} "field_content_type" => "free" "field_content_mode" => "text" "field_page_content_mode" => "" "field_content_text_checked" => null "field_page_content_text_checked" => "0" "field_solution_author" => "Gemini 2.5 Pro" "field_moderator" => "tolik" "field_edition_type" => "solution" "field_root_dir" => "2-" "field_responsible" => Illuminate\Database\Eloquent\Collection {#1148 …2} "field_comment" => null "field_similar_book" => Illuminate\Database\Eloquent\Collection {#1149 …2} "field_process_formula" => "katex" "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1150 …2} "field_content_source" => null ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "text" => "<p><strong>Найдите ошибку в преобразованиях Алихана</strong></p><p>Алихан получил задание упростить выражение $ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.</p><p>Приступая к решению, он совершил ошибку в первом же шаге преобразования, неверно применив формулу для произведения синусов. В его решении слагаемое $ - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $ было преобразовано с использованием неверного равенства $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = (\cos\alpha + \cos\beta) $.</p><p>Правильная формула преобразования произведения синусов в сумму (разность) косинусов выглядит так: $ 2\sin A \sin B = \cos(A-B) - \cos(A+B) $.</p><p>Применяя эту формулу к нашему случаю, где $ A = \frac{\alpha+\beta}{2} $ и $ B = \frac{\alpha-\beta}{2} $, получаем:</p><p>$ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\left(\frac{\alpha + \beta}{2} - \frac{\alpha - \beta}{2}\right) - \cos\left(\frac{\alpha + \beta}{2} + \frac{\alpha - \beta}{2}\right) = \cos\beta - \cos\alpha $.</p><p>Таким образом, Алихан должен был использовать выражение $ (\cos\beta - \cos\alpha) $ вместо $ (\cos\alpha + \cos\beta) $, что и привело к неверному конечному результату.</p><p><strong>Ответ:</strong> Ошибка Алихана заключается в неверном применении формулы преобразования произведения синусов в сумму. Он заменил выражение $2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2}$ на $(\cos\alpha + \cos\beta)$, в то время как правильное преобразование дает $(\cos\beta - \cos\alpha)$.</p><p><strong>Выполните задание правильно</strong></p><p>Упростим исходное выражение, используя правильные тригонометрические формулы.</p><p>Исходное выражение: $ E = \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.</p><p><strong>1.</strong> Преобразуем первые два слагаемых, используя формулу понижения степени $ \sin^2 x = \frac{1-\cos(2x)}{2} $:</p><p>$ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} = \frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} $</p><p>$ = \frac{1 - \cos(\alpha - \beta) + 1 - \cos(\alpha + \beta)}{2} = \frac{2 - (\cos(\alpha - \beta) + \cos(\alpha + \beta))}{2} $</p><p><strong>2.</strong> Применим формулу суммы косинусов $ \cos(\alpha - \beta) + \cos(\alpha + \beta) = 2\cos\alpha\cos\beta $. Подставим это в выражение:</p><p>$ \frac{2 - 2\cos\alpha\cos\beta}{2} = 1 - \cos\alpha\cos\beta $.</p><p><strong>3.</strong> Теперь преобразуем третье слагаемое, используя правильную формулу произведения синусов $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\beta - \cos\alpha $:</p><p>$ -2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} \cdot \cos\beta = -(\cos\beta - \cos\alpha) \cdot \cos\beta = -\cos^2\beta + \cos\alpha\cos\beta $.</p><p><strong>4.</strong> Сложим результаты преобразований:</p><p>$ E = (1 - \cos\alpha\cos\beta) + (-\cos^2\beta + \cos\alpha\cos\beta) $</p><p>$ E = 1 - \cos\alpha\cos\beta - \cos^2\beta + \cos\alpha\cos\beta $</p><p>$ E = 1 - \cos^2\beta $.</p><p><strong>5.</strong> Используя основное тригонометрическое тождество $ \sin^2\beta + \cos^2\beta = 1 $, получаем окончательный результат:</p><p>$ E = \sin^2\beta $.</p><p><strong>Ответ:</strong> $ \sin^2\beta $.</p>" ] #original: array:6 [ "id" => 1554420 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1144} "task" => array:2 [ "refs" => "1108565" "type" => "task" ] "text" => "<p><strong>Найдите ошибку в преобразованиях Алихана</strong></p><p>Алихан получил задание упростить выражение $ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.</p><p>Приступая к решению, он совершил ошибку в первом же шаге преобразования, неверно применив формулу для произведения синусов. В его решении слагаемое $ - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $ было преобразовано с использованием неверного равенства $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = (\cos\alpha + \cos\beta) $.</p><p>Правильная формула преобразования произведения синусов в сумму (разность) косинусов выглядит так: $ 2\sin A \sin B = \cos(A-B) - \cos(A+B) $.</p><p>Применяя эту формулу к нашему случаю, где $ A = \frac{\alpha+\beta}{2} $ и $ B = \frac{\alpha-\beta}{2} $, получаем:</p><p>$ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\left(\frac{\alpha + \beta}{2} - \frac{\alpha - \beta}{2}\right) - \cos\left(\frac{\alpha + \beta}{2} + \frac{\alpha - \beta}{2}\right) = \cos\beta - \cos\alpha $.</p><p>Таким образом, Алихан должен был использовать выражение $ (\cos\beta - \cos\alpha) $ вместо $ (\cos\alpha + \cos\beta) $, что и привело к неверному конечному результату.</p><p><strong>Ответ:</strong> Ошибка Алихана заключается в неверном применении формулы преобразования произведения синусов в сумму. Он заменил выражение $2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2}$ на $(\cos\alpha + \cos\beta)$, в то время как правильное преобразование дает $(\cos\beta - \cos\alpha)$.</p><p><strong>Выполните задание правильно</strong></p><p>Упростим исходное выражение, используя правильные тригонометрические формулы.</p><p>Исходное выражение: $ E = \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.</p><p><strong>1.</strong> Преобразуем первые два слагаемых, используя формулу понижения степени $ \sin^2 x = \frac{1-\cos(2x)}{2} $:</p><p>$ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} = \frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} $</p><p>$ = \frac{1 - \cos(\alpha - \beta) + 1 - \cos(\alpha + \beta)}{2} = \frac{2 - (\cos(\alpha - \beta) + \cos(\alpha + \beta))}{2} $</p><p><strong>2.</strong> Применим формулу суммы косинусов $ \cos(\alpha - \beta) + \cos(\alpha + \beta) = 2\cos\alpha\cos\beta $. Подставим это в выражение:</p><p>$ \frac{2 - 2\cos\alpha\cos\beta}{2} = 1 - \cos\alpha\cos\beta $.</p><p><strong>3.</strong> Теперь преобразуем третье слагаемое, используя правильную формулу произведения синусов $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\beta - \cos\alpha $:</p><p>$ -2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} \cdot \cos\beta = -(\cos\beta - \cos\alpha) \cdot \cos\beta = -\cos^2\beta + \cos\alpha\cos\beta $.</p><p><strong>4.</strong> Сложим результаты преобразований:</p><p>$ E = (1 - \cos\alpha\cos\beta) + (-\cos^2\beta + \cos\alpha\cos\beta) $</p><p>$ E = 1 - \cos\alpha\cos\beta - \cos^2\beta + \cos\alpha\cos\beta $</p><p>$ E = 1 - \cos^2\beta $.</p><p><strong>5.</strong> Используя основное тригонометрическое тождество $ \sin^2\beta + \cos^2\beta = 1 $, получаем окончательный результат:</p><p>$ E = \sin^2\beta $.</p><p><strong>Ответ:</strong> $ \sin^2\beta $.</p>" ] #changes: [] #casts: [] #classCastCache: [] 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+usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "page" => Illuminate\Database\Eloquent\Collection {#1429 #items: array:1 [ 0 => App\Models\BookPage {#1183 #connection: "mysql" #table: "book_pages" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:21 [ "id" => 1097967 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/page-225" "field_display_title" => "225" "field_folder" => "folder1" "field_image_name" => "225" "field_branch_parent" => Illuminate\Database\Eloquent\Collection {#1187 #items: [] #escapeWhenCastingToString: false } "field_weight" => "0" "field_book_parent" => Illuminate\Database\Eloquent\Collection {#1186 #items: array:1 [ 0 => App\Models\Book {#1188 #connection: "mysql" #table: "books" #primaryKey: "id" #keyType: "int" +incrementing: false #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1189 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1191 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1193 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1195 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1199 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1200 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1202 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1204 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1206 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1207 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1208 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1209 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1210 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1211 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1212 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1213 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1214 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1215 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #original: array:50 [ "id" => 4298 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_tree_default_status" => "tasks" "field_pages_status" => null "field_subject" => Illuminate\Database\Eloquent\Collection {#1189 …2} "field_class" => Illuminate\Database\Eloquent\Collection {#1191 …2} "field_publisher" => Illuminate\Database\Eloquent\Collection {#1193 …2} "field_author" => Illuminate\Database\Eloquent\Collection {#1195 …2} "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1199 …2} "field_book_type" => Illuminate\Database\Eloquent\Collection {#1200 …2} "field_country" => Illuminate\Database\Eloquent\Collection {#1202 …2} "field_city" => Illuminate\Database\Eloquent\Collection {#1204 …2} "field_series" => Illuminate\Database\Eloquent\Collection {#1206 …2} "field_umk" => Illuminate\Database\Eloquent\Collection {#1207 …2} "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1208 …2} "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1209 …2} "field_publication_number" => null "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1210 …2} "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1211 …2} "field_under_the_edition_degree" => null "field_cover_description" => null "field_publication_year" => "2019" "field_publication_year_until" => null "field_part" => "" "field_part_writing" => "" "field_second_foreign_language" => null "field_for_whom" => "Учебник для учащихся 9 класса общеобразовательных школ" "field_allowed" => "Рекомендовано Министерством образования и науки Республики Казахстан" "field_reserve_field" => null "field_link_to_source" => null "field_tasks_count" => "1291" "field_priority" => "4" "field_default_folder" => "/algebra_09/soltan-u19/" "field_isbn" => "978-601-317-424-2" "field_cover" => array:1 [ …1] "field_cover_alts" => array:1 [ …1] "field_covers" => array:1 [ …1] "field_popular_book" => null "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1212 …2} "field_new_book" => Illuminate\Database\Eloquent\Collection {#1213 …2} "field_old_book" => Illuminate\Database\Eloquent\Collection {#1214 …2} "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik" "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1215 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "breadcrumbs" => array:3 [ …3] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "edition_groups" => Illuminate\Database\Eloquent\Collection {#1216 #items: [] #escapeWhenCastingToString: false } "content" => Illuminate\Database\Eloquent\Collection {#1217 #items: array:1 [ 0 => App\Models\Element {#1218 #connection: "mysql" #table: "elements" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:6 [ "id" => 1261118 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1219 …2} "book_page" => array:2 [ …2] "img" => array:1 [ …1] ] #original: array:6 [ "id" => 1261118 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "edition" => Illuminate\Database\Eloquent\Collection {#1219 …2} "book_page" => array:2 [ …2] "img" => array:1 [ …1] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } "next" => array:2 [ "refs" => "1097968" "type" => "book_page" ] "previous" => array:2 [ "refs" => "1097966" "type" => "book_page" ] "tasks" => Illuminate\Database\Eloquent\Collection {#1226 #items: array:7 [ 0 => App\Models\Task {#1227 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108559 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-813" "field_display_title" => "813" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1228 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1230 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1231 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1264 …2} "content" => Illuminate\Database\Eloquent\Collection {#1329 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1348 …2} "page" => array:2 [ …2] ] #original: array:24 [ "id" => 1108559 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-813" "field_display_title" => "813" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1228 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1230 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1231 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1264 …2} "content" => Illuminate\Database\Eloquent\Collection {#1329 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1348 …2} "page" => array:2 [ …2] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 1 => App\Models\Task {#1349 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108560 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-814" "field_display_title" => "814" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1350 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1351 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1352 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1353 …2} "content" => Illuminate\Database\Eloquent\Collection {#1354 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1361 …2} "page" => array:2 [ …2] ] #original: array:24 [ "id" => 1108560 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-814" "field_display_title" => "814" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1350 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1351 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1352 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1353 …2} "content" => Illuminate\Database\Eloquent\Collection {#1354 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1361 …2} "page" => array:2 [ …2] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 2 => App\Models\Task {#1362 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108561 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-815" "field_display_title" => "815" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1363 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1364 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1365 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1366 …2} "content" => Illuminate\Database\Eloquent\Collection {#1367 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1374 …2} "page" => array:2 [ …2] ] #original: array:24 [ "id" => 1108561 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-815" "field_display_title" => "815" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1363 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1364 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1365 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1366 …2} "content" => Illuminate\Database\Eloquent\Collection {#1367 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1374 …2} "page" => array:2 [ …2] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 3 => App\Models\Task {#1375 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108562 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-816" "field_display_title" => "816" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1376 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1377 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1378 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1379 …2} "content" => Illuminate\Database\Eloquent\Collection {#1380 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1387 …2} "page" => array:2 [ …2] ] #original: array:24 [ "id" => 1108562 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-816" "field_display_title" => "816" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1376 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1377 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1378 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1379 …2} "content" => Illuminate\Database\Eloquent\Collection {#1380 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1387 …2} "page" => array:2 [ …2] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 4 => App\Models\Task {#1388 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108563 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-817" "field_display_title" => "817" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1389 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1390 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1391 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1392 …2} "content" => Illuminate\Database\Eloquent\Collection {#1393 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1400 …2} "page" => array:2 [ …2] ] #original: array:24 [ "id" => 1108563 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => null "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-817" "field_display_title" => "817" "field_outside_task" => null "field_task_type" => Illuminate\Database\Eloquent\Collection {#1389 …2} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1390 …2} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#1391 …2} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1392 …2} "content" => Illuminate\Database\Eloquent\Collection {#1393 …2} "next" => array:2 [ …2] "previous" => array:2 [ …2] "book" => Illuminate\Database\Eloquent\Collection {#1400 …2} "page" => array:2 [ …2] ] #changes: [] #casts: [] #classCastCache: [] #attributeCastCache: [] #dateFormat: null #appends: [] #dispatchesEvents: [] #observables: [] #relations: [] #touches: [] +timestamps: true +usesUniqueIds: false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } 5 => App\Models\Task {#1401 #connection: "mysql" #table: "tasks" #primaryKey: "id" #keyType: "int" +incrementing: true #with: [] #withCount: [] +preventsLazyLoading: false #perPage: 15 +exists: true +wasRecentlyCreated: false #escapeWhenCastingToString: false #attributes: array:24 [ "id" => 1108564 "created_at" => 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false #hidden: [] #visible: [] #fillable: [] #guarded: array:1 [ 0 => "*" ] } ] #escapeWhenCastingToString: false } ] #original: array:24 [ "id" => 1108565 "created_at" => "2026-04-10 13:58:26" "updated_at" => null "field_page_start" => "225" "field_page_end" => "226" "field_url" => "/9-klass/algebra/kokshetau-soltan-uchebnik/1-819" "field_display_title" => "819" "field_outside_task" => "0" "field_task_type" => Illuminate\Database\Eloquent\Collection {#331} "field_metatags_title" => null "field_metatags_description" => null "field_h1" => null "field_description_top" => null "field_description_bottom" => null "field_match" => null "breadcrumbs" => [] "edition_groups" => Illuminate\Database\Eloquent\Collection {#1026} "top_parent_branch" => Illuminate\Database\Eloquent\Collection {#342} "parent_branches" => Illuminate\Database\Eloquent\Collection {#1061} "content" => Illuminate\Database\Eloquent\Collection {#1126} "next" => array:2 [ "refs" => "1108566" "type" => "task" ] "previous" => 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№819 (с. 225)
Условие. №819 (с. 225)
скриншот условия
819. Алихан получил задание: упростить выражение
$\sin^2 \frac{\alpha - \beta}{2} + \sin^2 \frac{\alpha + \beta}{2} - 2\sin \frac{\alpha + \beta}{2} \cdot \sin \frac{\alpha - \beta}{2} \cdot \cos \beta.$ Он провел следующие преобразования этого выражения:
$\frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} - (\cos \alpha + \cos \beta) \cdot \cos \beta =$
$= 1 - \frac{\cos(\alpha - \beta) + \cos(\alpha + \beta)}{2} - \cos \alpha \cdot \cos \beta - \cos^2\beta =$
$= 1 - \cos \alpha \cdot \cos \beta - \cos \alpha \cdot \cos \beta - \cos^2\beta = \sin^2\beta - 2\cos \alpha \cdot \cos \beta.$
Софии было поручено проверить, получил ли Алихан правильный ответ. Она вместо $\alpha$ и $\beta$ подставила в исходное и последнее выражение $0$ и получила неверное равенство $0 = -2.$
Следовательно, ответ неправильный. Найдите ошибку в преобразованиях Алихана и выполните задание правильно.
Решение. №819 (с. 225)
Решение 2 (rus). №819 (с. 225)
Найдите ошибку в преобразованиях Алихана
Алихан получил задание упростить выражение $ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.
Приступая к решению, он совершил ошибку в первом же шаге преобразования, неверно применив формулу для произведения синусов. В его решении слагаемое $ - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $ было преобразовано с использованием неверного равенства $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = (\cos\alpha + \cos\beta) $.
Правильная формула преобразования произведения синусов в сумму (разность) косинусов выглядит так: $ 2\sin A \sin B = \cos(A-B) - \cos(A+B) $.
Применяя эту формулу к нашему случаю, где $ A = \frac{\alpha+\beta}{2} $ и $ B = \frac{\alpha-\beta}{2} $, получаем:
$ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\left(\frac{\alpha + \beta}{2} - \frac{\alpha - \beta}{2}\right) - \cos\left(\frac{\alpha + \beta}{2} + \frac{\alpha - \beta}{2}\right) = \cos\beta - \cos\alpha $.
Таким образом, Алихан должен был использовать выражение $ (\cos\beta - \cos\alpha) $ вместо $ (\cos\alpha + \cos\beta) $, что и привело к неверному конечному результату.
Ответ: Ошибка Алихана заключается в неверном применении формулы преобразования произведения синусов в сумму. Он заменил выражение $2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2}$ на $(\cos\alpha + \cos\beta)$, в то время как правильное преобразование дает $(\cos\beta - \cos\alpha)$.
Выполните задание правильно
Упростим исходное выражение, используя правильные тригонометрические формулы.
Исходное выражение: $ E = \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} - 2\sin\frac{\alpha + \beta}{2} \cdot \sin\frac{\alpha - \beta}{2} \cdot \cos\beta $.
1. Преобразуем первые два слагаемых, используя формулу понижения степени $ \sin^2 x = \frac{1-\cos(2x)}{2} $:
$ \sin^2\frac{\alpha - \beta}{2} + \sin^2\frac{\alpha + \beta}{2} = \frac{1 - \cos(\alpha - \beta)}{2} + \frac{1 - \cos(\alpha + \beta)}{2} $
$ = \frac{1 - \cos(\alpha - \beta) + 1 - \cos(\alpha + \beta)}{2} = \frac{2 - (\cos(\alpha - \beta) + \cos(\alpha + \beta))}{2} $
2. Применим формулу суммы косинусов $ \cos(\alpha - \beta) + \cos(\alpha + \beta) = 2\cos\alpha\cos\beta $. Подставим это в выражение:
$ \frac{2 - 2\cos\alpha\cos\beta}{2} = 1 - \cos\alpha\cos\beta $.
3. Теперь преобразуем третье слагаемое, используя правильную формулу произведения синусов $ 2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} = \cos\beta - \cos\alpha $:
$ -2\sin\frac{\alpha + \beta}{2} \sin\frac{\alpha - \beta}{2} \cdot \cos\beta = -(\cos\beta - \cos\alpha) \cdot \cos\beta = -\cos^2\beta + \cos\alpha\cos\beta $.
4. Сложим результаты преобразований:
$ E = (1 - \cos\alpha\cos\beta) + (-\cos^2\beta + \cos\alpha\cos\beta) $
$ E = 1 - \cos\alpha\cos\beta - \cos^2\beta + \cos\alpha\cos\beta $
$ E = 1 - \cos^2\beta $.
5. Используя основное тригонометрическое тождество $ \sin^2\beta + \cos^2\beta = 1 $, получаем окончательный результат:
$ E = \sin^2\beta $.
Ответ: $ \sin^2\beta $.
Другие задания:
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