Номер 204, страница 61 - гдз по геометрии 10-11 класс учебник Атанасян, Бутузов

Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета

Авторы: Атанасян Л. С., Бутузов В. Ф., Кадомцев С. Б., Позняк Э. Г., Киселёва Л. С.

Тип: Учебник

Издательство: Просвещение

Год издания: 2019 - 2026

Уровень обучения: базовый и углублённый

Цвет обложки: коричневый с ромбами

ISBN: 978-5-09-103606-0 (2023)

Допущено Министерством просвещения Российской Федерации

Математика: алгебра и начала математического анализа, геометрия

Глава 2. Перпендикулярность прямых и плоскостей. Параграф 3. Двугранный угол. Перпендикулярность плоскостей, дополнительные задачи - номер 204, страница 61.

App\Models\Task {#1030 // resources/views/models/task/default.blade.php
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        0 => App\Models\Term {#1036
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                        1 => App\Models\Term {#1054
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                        4 => App\Models\Term {#1062
                          #connection: "mysql"
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                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1066
                      #items: array:1 [
                        0 => App\Models\Term {#1067
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
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                          #hidden: []
                          #visible: []
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                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1068
                      #items: array:1 [
                        0 => App\Models\Term {#1069
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
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                          +exists: true
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                          #attributes: array:6 [ …6]
                          #original: array:6 [ …6]
                          #changes: []
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                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1070
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1071
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1072
                      #items: array:1 [
                        0 => App\Models\Term {#1073
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
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                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:6 [ …6]
                          #original: array:6 [ …6]
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                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
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                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1074
                      #items: array:1 [
                        0 => App\Models\Term {#1075
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
                          +incrementing: false
                          #with: []
                          #withCount: []
                          +preventsLazyLoading: false
                          #perPage: 15
                          +exists: true
                          +wasRecentlyCreated: false
                          #escapeWhenCastingToString: false
                          #attributes: array:10 [ …10]
                          #original: array:10 [ …10]
                          #changes: []
                          #casts: []
                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
                          +usesUniqueIds: false
                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_publication_number" => "11"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1076
                      #items: array:1 [
                        0 => App\Models\Term {#1077
                          #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 [ …6]
                          #original: array:6 [ …6]
                          #changes: []
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                          #classCastCache: []
                          #attributeCastCache: []
                          #dateFormat: null
                          #appends: []
                          #dispatchesEvents: []
                          #observables: []
                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
                          #fillable: []
                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1078
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "с ромбами"
                    "field_publication_year" => "2019"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебник для общеобразовательных организаций"
                    "field_allowed" => "Допущено Министерством просвещения Российской Федерации"
                    "field_reserve_field" => "Математика: алгебра и начала математического анализа, геометрия"
                    "field_link_to_source" => null
                    "field_tasks_count" => "1147"
                    "field_priority" => "12"
                    "field_default_folder" => "/geometrija_10/atanasjan-u23/"
                    "field_isbn" => "978-5-09-103606-0 (2023)"
                    "field_cover" => array:1 [
                      0 => "/media/geometrija_10/atanasjan-u23/covers/cover1.webp?ts=1739363242"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/geometrija_10/atanasjan-u23/covers/cover1.webp?ts=1739363242"
                        "alt" => ""
                        "width" => "1200"
                        "height" => "1661"
                      ]
                    ]
                    "field_popular_book" => null
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1079
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1080
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_old_book" => Illuminate\Database\Eloquent\Collection {#1081
                      #items: []
                      #escapeWhenCastingToString: false
                    }
                    "field_url" => "/10-klass/geometrija/atanasjan-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1082
                      #items: array:1 [
                        0 => App\Models\Term {#1083
                          #connection: "mysql"
                          #table: "terms"
                          #primaryKey: "id"
                          #keyType: "int"
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                          #attributes: array:6 [ …6]
                          #original: array:6 [ …6]
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                          #dateFormat: null
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                          #dispatchesEvents: []
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                          #relations: []
                          #touches: []
                          +timestamps: true
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                          #hidden: []
                          #visible: []
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                          #guarded: array:1 [ …1]
                        }
                      ]
                      #escapeWhenCastingToString: false
                    }
                    "field_metatags_title" => null
                    "field_metatags_description" => null
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                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
                      "class" => 381
                      "subject" => 543
                      "class_subject" => 392
                    ]
                  ]
                  #original: array:50 [
                    "id" => 36
                    "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 {#1051}
                    "field_class" => Illuminate\Database\Eloquent\Collection {#1052}
                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1055}
                    "field_author" => Illuminate\Database\Eloquent\Collection {#1057}
                    "field_author_foreign" => Illuminate\Database\Eloquent\Collection {#1063}
                    "field_book_type" => Illuminate\Database\Eloquent\Collection {#1064}
                    "field_country" => Illuminate\Database\Eloquent\Collection {#1066}
                    "field_city" => Illuminate\Database\Eloquent\Collection {#1068}
                    "field_series" => Illuminate\Database\Eloquent\Collection {#1070}
                    "field_umk" => Illuminate\Database\Eloquent\Collection {#1071}
                    "field_level_of_education" => Illuminate\Database\Eloquent\Collection {#1072}
                    "field_standart_of_education" => Illuminate\Database\Eloquent\Collection {#1074}
                    "field_publication_number" => "11"
                    "field_publication_type" => Illuminate\Database\Eloquent\Collection {#1076}
                    "field_under_the_edition" => Illuminate\Database\Eloquent\Collection {#1078}
                    "field_under_the_edition_degree" => null
                    "field_cover_description" => "с ромбами"
                    "field_publication_year" => "2019"
                    "field_publication_year_until" => null
                    "field_part" => ""
                    "field_part_writing" => ""
                    "field_second_foreign_language" => null
                    "field_for_whom" => "Учебник для общеобразовательных организаций"
                    "field_allowed" => "Допущено Министерством просвещения Российской Федерации"
                    "field_reserve_field" => "Математика: алгебра и начала математического анализа, геометрия"
                    "field_link_to_source" => null
                    "field_tasks_count" => "1147"
                    "field_priority" => "12"
                    "field_default_folder" => "/geometrija_10/atanasjan-u23/"
                    "field_isbn" => "978-5-09-103606-0 (2023)"
                    "field_cover" => array:1 [
                      0 => "/media/geometrija_10/atanasjan-u23/covers/cover1.webp?ts=1739363242"
                    ]
                    "field_cover_alts" => array:1 [
                      0 => ""
                    ]
                    "field_covers" => array:1 [
                      0 => array:4 [
                        "path" => "/media/geometrija_10/atanasjan-u23/covers/cover1.webp?ts=1739363242"
                        "alt" => ""
                        "width" => "1200"
                        "height" => "1661"
                      ]
                    ]
                    "field_popular_book" => null
                    "field_recommended_books" => Illuminate\Database\Eloquent\Collection {#1079}
                    "field_new_book" => Illuminate\Database\Eloquent\Collection {#1080}
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                    "field_url" => "/10-klass/geometrija/atanasjan-uchebnik"
                    "field_cover_color" => Illuminate\Database\Eloquent\Collection {#1082}
                    "field_metatags_title" => null
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                    "field_description_bottom" => null
                    "breadcrumbs" => array:3 [
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                    ]
                  ]
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                    0 => "*"
                  ]
                }
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1084
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 744374
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Перпендикулярность прямых и плоскостей"
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1050}
            "field_page_start" => "36"
            "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
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            "field_branch_cover" => []
            "field_branch_covers" => []
            "book" => Illuminate\Database\Eloquent\Collection {#1086}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1084}
          ]
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          #dateFormat: null
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          +timestamps: true
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          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
      ]
      #escapeWhenCastingToString: false
    }
    "parent_branches" => Illuminate\Database\Eloquent\Collection {#1121
      #items: array:2 [
        0 => App\Models\Branch {#1129
          #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" => 744374
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Перпендикулярность прямых и плоскостей"
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1130
              #items: array:1 [
                0 => App\Models\Term {#1047}
              ]
              #escapeWhenCastingToString: false
            }
            "field_page_start" => "36"
            "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 {#1131
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1132
              #items: []
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 744374
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Перпендикулярность прямых и плоскостей"
            "field_branch_order" => "2"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1130}
            "field_page_start" => "36"
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            "field_display_branch_in_title" => "1"
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            "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 {#1131}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1132}
          ]
          #changes: []
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          #classCastCache: []
          #attributeCastCache: []
          #dateFormat: null
          #appends: []
          #dispatchesEvents: []
          #observables: []
          #relations: []
          #touches: []
          +timestamps: true
          +usesUniqueIds: false
          #hidden: []
          #visible: []
          #fillable: []
          #guarded: array:1 [
            0 => "*"
          ]
        }
        1 => App\Models\Branch {#1133
          #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" => 744379
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Двугранный угол. Перпендикулярность плоскостей, дополнительные задачи"
            "field_branch_order" => "3"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1137
              #items: array:1 [
                0 => App\Models\Term {#1134
                  #connection: "mysql"
                  #table: "terms"
                  #primaryKey: "id"
                  #keyType: "int"
                  +incrementing: false
                  #with: []
                  #withCount: []
                  +preventsLazyLoading: false
                  #perPage: 15
                  +exists: true
                  +wasRecentlyCreated: false
                  #escapeWhenCastingToString: false
                  #attributes: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "field_short_name" => "§"
                  ]
                  #original: array:7 [
                    "id" => 32
                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "name" => "Параграф"
                    "field_cases" => array:6 [ …6]
                    "field_page_check_not_needed" => null
                    "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_page_start" => "61"
            "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 {#1136
              #items: array:1 [
                0 => App\Models\Book {#1049}
              ]
              #escapeWhenCastingToString: false
            }
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1135
              #items: array:1 [
                0 => App\Models\Branch {#1045}
              ]
              #escapeWhenCastingToString: false
            }
          ]
          #original: array:24 [
            "id" => 744379
            "created_at" => "2026-04-10 13:58:26"
            "updated_at" => null
            "field_display_title" => "Двугранный угол. Перпендикулярность плоскостей, дополнительные задачи"
            "field_branch_order" => "3"
            "field_url" => null
            "field_branch_type" => Illuminate\Database\Eloquent\Collection {#1137}
            "field_page_start" => "61"
            "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 {#1136}
            "branch_parent" => Illuminate\Database\Eloquent\Collection {#1135}
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      ]
      #escapeWhenCastingToString: false
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    "content" => Illuminate\Database\Eloquent\Collection {#1118
      #items: array:5 [
        0 => App\Models\Element {#1108
          #connection: "mysql"
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                  #connection: "mysql"
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                  #attributes: array:21 [
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                    "created_at" => "2026-04-10 13:58:26"
                    "updated_at" => null
                    "title" => "Условие"
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                    "field_publisher" => Illuminate\Database\Eloquent\Collection {#1107 …2}
                    "field_content_type" => "free"
                    "field_content_mode" => "text, image"
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                    "field_page_content_text_checked" => "0"
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                    "field_edition_type" => "statement"
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                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1102 …2}
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                    "id" => 2315
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            "edition" => Illuminate\Database\Eloquent\Collection {#1101}
            "task" => array:2 [
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              "type" => "task"
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            "text" => "<p> <b>204.</b> Прямая ОМ перпендикулярна к плоскости правильного треугольника ABC и проходит через центр О этого треугольника, <span class="long">ОМ = а, </span> <span class="long">∠MCO = φ. </span> Найдите: а) расстояние от точки М до каждой из вершин треугольника ABC и до прямых AB, ВС и СА; б) длину окружности, описанной около треугольника ABC; в) площадь треугольника ABC. </p>"
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        1 => App\Models\Element {#1087
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          #table: "elements"
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                    "created_at" => "2026-04-10 13:58:26"
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                    "field_edition_group" => Illuminate\Database\Eloquent\Collection {#1128 …2}
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                  ]
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            "text" => "<p><strong>а)</strong> Найти расстояние от точки $M$ до каждой из вершин треугольника $ABC$ и до прямых $AB, BC$ и $CA$.</p><p>Поскольку прямая $OM$ перпендикулярна плоскости правильного треугольника $ABC$ ($OM \perp (ABC)$) и проходит через его центр $O$, то $OM$ перпендикулярна любой прямой в этой плоскости, проходящей через $O$. Следовательно, треугольник $\triangle MOC$ является прямоугольным с прямым углом $\angle MOC = 90^\circ$.</p><p><b>1. Расстояние от точки $M$ до вершин треугольника.</b></p><p>Так как $O$ — центр правильного треугольника $ABC$, он равноудален от его вершин, то есть $OA = OB = OC = R$, где $R$ — радиус описанной окружности. Рассмотрим прямоугольные треугольники $\triangle MOA$, $\triangle MOB$ и $\triangle MOC$. У них общий катет $OM=a$ и равные вторые катеты $OA = OB = OC$. Следовательно, эти треугольники равны по двум катетам, а значит, равны и их гипотенузы: $MA = MB = MC$.</p><p>Найдем длину гипотенузы $MC$ из прямоугольного треугольника $\triangle MOC$. Известны катет $OM = a$ и противолежащий ему угол $\angle MCO = \phi$. По определению синуса в прямоугольном треугольнике:</p><p>$\sin(\angle MCO) = \frac{OM}{MC}$</p><p>$\sin(\phi) = \frac{a}{MC}$</p><p>Отсюда находим расстояние от точки $M$ до каждой из вершин:</p><p>$MA = MB = MC = \frac{a}{\sin(\phi)}$</p><p><b>2. Расстояние от точки $M$ до прямых, содержащих стороны треугольника.</b></p><p>В силу симметрии, расстояния от точки $M$ до прямых $AB, BC$ и $CA$ равны. Найдем расстояние от точки $M$ до прямой $BC$. Расстояние от точки до прямой — это длина перпендикуляра. Пусть $K$ — середина стороны $BC$. В правильном треугольнике медиана $AK$ является и высотой, поэтому $OK \perp BC$. Отрезок $OK$ является радиусом вписанной в треугольник окружности ($OK = r$).</p><p>Согласно теореме о трех перпендикулярах, так как $OM$ — перпендикуляр к плоскости $(ABC)$, $MK$ — наклонная, а $OK$ — ее проекция на эту плоскость, и при этом проекция $OK$ перпендикулярна прямой $BC$, то и сама наклонная $MK$ перпендикулярна прямой $BC$ ($MK \perp BC$). Таким образом, длина отрезка $MK$ и есть искомое расстояние.</p><p>Найдем длину $MK$ из прямоугольного треугольника $\triangle MOK$ (где $\angle MOK = 90^\circ$) по теореме Пифагора: $MK^2 = OM^2 + OK^2$.</p><p>Для этого сначала найдем $OK = r$. В прямоугольном $\triangle MOC$ найдем катет $OC = R$ (радиус описанной окружности):</p><p>$\cot(\angle MCO) = \frac{OC}{OM} \implies \cot(\phi) = \frac{R}{a} \implies R = a \cot(\phi)$</p><p>Для правильного треугольника радиус вписанной окружности в два раза меньше радиуса описанной: $r = \frac{R}{2}$.</p><p>$OK = r = \frac{a \cot(\phi)}{2}$</p><p>Теперь можем вычислить $MK$:</p><p>$MK^2 = a^2 + \left(\frac{a \cot(\phi)}{2}\right)^2 = a^2 + \frac{a^2 \cot^2(\phi)}{4} = a^2\left(1 + \frac{\cot^2(\phi)}{4}\right) = \frac{a^2(4 + \cot^2(\phi))}{4}$</p><p>$MK = \sqrt{\frac{a^2(4 + \cot^2(\phi))}{4}} = \frac{a}{2}\sqrt{4 + \cot^2(\phi)}$</p><p>Ответ: расстояние от точки $M$ до каждой из вершин треугольника $ABC$ равно $\frac{a}{\sin(\phi)}$, а расстояние от точки $M$ до каждой из прямых $AB, BC, CA$ равно $\frac{a}{2}\sqrt{4 + \cot^2(\phi)}$.</p><p><strong>б)</strong> Найти длину окружности, описанной около треугольника $ABC$.</p><p>Длина окружности $L$ вычисляется по формуле $L = 2\pi R$, где $R$ — радиус описанной окружности.</p><p>В пункте <strong>а)</strong> мы нашли, что $R = a \cot(\phi)$.</p><p>Подставим это значение в формулу:</p><p>$L = 2\pi (a \cot(\phi)) = 2\pi a \cot(\phi)$</p><p>Ответ: $2\pi a \cot(\phi)$.</p><p><strong>в)</strong> Найти площадь треугольника $ABC$.</p><p>Площадь правильного треугольника $S$ можно вычислить через радиус описанной окружности $R$ по формуле:</p><p>$S = \frac{3\sqrt{3}}{4}R^2$</p><p>Используя найденное ранее значение $R = a \cot(\phi)$, получаем:</p><p>$S = \frac{3\sqrt{3}}{4}(a \cot(\phi))^2 = \frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$</p><p>Ответ: $\frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$.</p>"
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            "text" => "<p><strong>а)</strong> Найти расстояние от точки $M$ до каждой из вершин треугольника $ABC$ и до прямых $AB, BC$ и $CA$.</p><p>Поскольку прямая $OM$ перпендикулярна плоскости правильного треугольника $ABC$ ($OM \perp (ABC)$) и проходит через его центр $O$, то $OM$ перпендикулярна любой прямой в этой плоскости, проходящей через $O$. Следовательно, треугольник $\triangle MOC$ является прямоугольным с прямым углом $\angle MOC = 90^\circ$.</p><p><b>1. Расстояние от точки $M$ до вершин треугольника.</b></p><p>Так как $O$ — центр правильного треугольника $ABC$, он равноудален от его вершин, то есть $OA = OB = OC = R$, где $R$ — радиус описанной окружности. Рассмотрим прямоугольные треугольники $\triangle MOA$, $\triangle MOB$ и $\triangle MOC$. У них общий катет $OM=a$ и равные вторые катеты $OA = OB = OC$. Следовательно, эти треугольники равны по двум катетам, а значит, равны и их гипотенузы: $MA = MB = MC$.</p><p>Найдем длину гипотенузы $MC$ из прямоугольного треугольника $\triangle MOC$. Известны катет $OM = a$ и противолежащий ему угол $\angle MCO = \phi$. По определению синуса в прямоугольном треугольнике:</p><p>$\sin(\angle MCO) = \frac{OM}{MC}$</p><p>$\sin(\phi) = \frac{a}{MC}$</p><p>Отсюда находим расстояние от точки $M$ до каждой из вершин:</p><p>$MA = MB = MC = \frac{a}{\sin(\phi)}$</p><p><b>2. Расстояние от точки $M$ до прямых, содержащих стороны треугольника.</b></p><p>В силу симметрии, расстояния от точки $M$ до прямых $AB, BC$ и $CA$ равны. Найдем расстояние от точки $M$ до прямой $BC$. Расстояние от точки до прямой — это длина перпендикуляра. Пусть $K$ — середина стороны $BC$. В правильном треугольнике медиана $AK$ является и высотой, поэтому $OK \perp BC$. Отрезок $OK$ является радиусом вписанной в треугольник окружности ($OK = r$).</p><p>Согласно теореме о трех перпендикулярах, так как $OM$ — перпендикуляр к плоскости $(ABC)$, $MK$ — наклонная, а $OK$ — ее проекция на эту плоскость, и при этом проекция $OK$ перпендикулярна прямой $BC$, то и сама наклонная $MK$ перпендикулярна прямой $BC$ ($MK \perp BC$). Таким образом, длина отрезка $MK$ и есть искомое расстояние.</p><p>Найдем длину $MK$ из прямоугольного треугольника $\triangle MOK$ (где $\angle MOK = 90^\circ$) по теореме Пифагора: $MK^2 = OM^2 + OK^2$.</p><p>Для этого сначала найдем $OK = r$. В прямоугольном $\triangle MOC$ найдем катет $OC = R$ (радиус описанной окружности):</p><p>$\cot(\angle MCO) = \frac{OC}{OM} \implies \cot(\phi) = \frac{R}{a} \implies R = a \cot(\phi)$</p><p>Для правильного треугольника радиус вписанной окружности в два раза меньше радиуса описанной: $r = \frac{R}{2}$.</p><p>$OK = r = \frac{a \cot(\phi)}{2}$</p><p>Теперь можем вычислить $MK$:</p><p>$MK^2 = a^2 + \left(\frac{a \cot(\phi)}{2}\right)^2 = a^2 + \frac{a^2 \cot^2(\phi)}{4} = a^2\left(1 + \frac{\cot^2(\phi)}{4}\right) = \frac{a^2(4 + \cot^2(\phi))}{4}$</p><p>$MK = \sqrt{\frac{a^2(4 + \cot^2(\phi))}{4}} = \frac{a}{2}\sqrt{4 + \cot^2(\phi)}$</p><p>Ответ: расстояние от точки $M$ до каждой из вершин треугольника $ABC$ равно $\frac{a}{\sin(\phi)}$, а расстояние от точки $M$ до каждой из прямых $AB, BC, CA$ равно $\frac{a}{2}\sqrt{4 + \cot^2(\phi)}$.</p><p><strong>б)</strong> Найти длину окружности, описанной около треугольника $ABC$.</p><p>Длина окружности $L$ вычисляется по формуле $L = 2\pi R$, где $R$ — радиус описанной окружности.</p><p>В пункте <strong>а)</strong> мы нашли, что $R = a \cot(\phi)$.</p><p>Подставим это значение в формулу:</p><p>$L = 2\pi (a \cot(\phi)) = 2\pi a \cot(\phi)$</p><p>Ответ: $2\pi a \cot(\phi)$.</p><p><strong>в)</strong> Найти площадь треугольника $ABC$.</p><p>Площадь правильного треугольника $S$ можно вычислить через радиус описанной окружности $R$ по формуле:</p><p>$S = \frac{3\sqrt{3}}{4}R^2$</p><p>Используя найденное ранее значение $R = a \cot(\phi)$, получаем:</p><p>$S = \frac{3\sqrt{3}}{4}(a \cot(\phi))^2 = \frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$</p><p>Ответ: $\frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$.</p>"
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№204 (с. 61)
Условие. №204 (с. 61)
скриншот условия
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Условие

204. Прямая ОМ перпендикулярна к плоскости правильного треугольника ABC и проходит через центр О этого треугольника, ОМ = а, ∠MCO = φ. Найдите: а) расстояние от точки М до каждой из вершин треугольника ABC и до прямых AB, ВС и СА; б) длину окружности, описанной около треугольника ABC; в) площадь треугольника ABC.

Решение 2. №204 (с. 61)
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Решение 2
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Решение 2 (продолжение 2)
Решение 3. №204 (с. 61)
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Решение 3
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Решение 3 (продолжение 2)
Решение 5. №204 (с. 61)
Геометрия, 10-11 класс Учебник, авторы: Атанасян Левон Сергеевич, Бутузов Валентин Фёдорович, Кадомцев Сергей Борисович, Позняк Эдуард Генрихович, Киселёва Людмила Сергеевна, издательство Просвещение, Москва, 2019, коричневого цвета, страница 61, номер 204, Решение 5
Решение 6. №204 (с. 61)

а) Найти расстояние от точки $M$ до каждой из вершин треугольника $ABC$ и до прямых $AB, BC$ и $CA$.

Поскольку прямая $OM$ перпендикулярна плоскости правильного треугольника $ABC$ ($OM \perp (ABC)$) и проходит через его центр $O$, то $OM$ перпендикулярна любой прямой в этой плоскости, проходящей через $O$. Следовательно, треугольник $\triangle MOC$ является прямоугольным с прямым углом $\angle MOC = 90^\circ$.

1. Расстояние от точки $M$ до вершин треугольника.

Так как $O$ — центр правильного треугольника $ABC$, он равноудален от его вершин, то есть $OA = OB = OC = R$, где $R$ — радиус описанной окружности. Рассмотрим прямоугольные треугольники $\triangle MOA$, $\triangle MOB$ и $\triangle MOC$. У них общий катет $OM=a$ и равные вторые катеты $OA = OB = OC$. Следовательно, эти треугольники равны по двум катетам, а значит, равны и их гипотенузы: $MA = MB = MC$.

Найдем длину гипотенузы $MC$ из прямоугольного треугольника $\triangle MOC$. Известны катет $OM = a$ и противолежащий ему угол $\angle MCO = \phi$. По определению синуса в прямоугольном треугольнике:

$\sin(\angle MCO) = \frac{OM}{MC}$

$\sin(\phi) = \frac{a}{MC}$

Отсюда находим расстояние от точки $M$ до каждой из вершин:

$MA = MB = MC = \frac{a}{\sin(\phi)}$

2. Расстояние от точки $M$ до прямых, содержащих стороны треугольника.

В силу симметрии, расстояния от точки $M$ до прямых $AB, BC$ и $CA$ равны. Найдем расстояние от точки $M$ до прямой $BC$. Расстояние от точки до прямой — это длина перпендикуляра. Пусть $K$ — середина стороны $BC$. В правильном треугольнике медиана $AK$ является и высотой, поэтому $OK \perp BC$. Отрезок $OK$ является радиусом вписанной в треугольник окружности ($OK = r$).

Согласно теореме о трех перпендикулярах, так как $OM$ — перпендикуляр к плоскости $(ABC)$, $MK$ — наклонная, а $OK$ — ее проекция на эту плоскость, и при этом проекция $OK$ перпендикулярна прямой $BC$, то и сама наклонная $MK$ перпендикулярна прямой $BC$ ($MK \perp BC$). Таким образом, длина отрезка $MK$ и есть искомое расстояние.

Найдем длину $MK$ из прямоугольного треугольника $\triangle MOK$ (где $\angle MOK = 90^\circ$) по теореме Пифагора: $MK^2 = OM^2 + OK^2$.

Для этого сначала найдем $OK = r$. В прямоугольном $\triangle MOC$ найдем катет $OC = R$ (радиус описанной окружности):

$\cot(\angle MCO) = \frac{OC}{OM} \implies \cot(\phi) = \frac{R}{a} \implies R = a \cot(\phi)$

Для правильного треугольника радиус вписанной окружности в два раза меньше радиуса описанной: $r = \frac{R}{2}$.

$OK = r = \frac{a \cot(\phi)}{2}$

Теперь можем вычислить $MK$:

$MK^2 = a^2 + \left(\frac{a \cot(\phi)}{2}\right)^2 = a^2 + \frac{a^2 \cot^2(\phi)}{4} = a^2\left(1 + \frac{\cot^2(\phi)}{4}\right) = \frac{a^2(4 + \cot^2(\phi))}{4}$

$MK = \sqrt{\frac{a^2(4 + \cot^2(\phi))}{4}} = \frac{a}{2}\sqrt{4 + \cot^2(\phi)}$

Ответ: расстояние от точки $M$ до каждой из вершин треугольника $ABC$ равно $\frac{a}{\sin(\phi)}$, а расстояние от точки $M$ до каждой из прямых $AB, BC, CA$ равно $\frac{a}{2}\sqrt{4 + \cot^2(\phi)}$.

б) Найти длину окружности, описанной около треугольника $ABC$.

Длина окружности $L$ вычисляется по формуле $L = 2\pi R$, где $R$ — радиус описанной окружности.

В пункте а) мы нашли, что $R = a \cot(\phi)$.

Подставим это значение в формулу:

$L = 2\pi (a \cot(\phi)) = 2\pi a \cot(\phi)$

Ответ: $2\pi a \cot(\phi)$.

в) Найти площадь треугольника $ABC$.

Площадь правильного треугольника $S$ можно вычислить через радиус описанной окружности $R$ по формуле:

$S = \frac{3\sqrt{3}}{4}R^2$

Используя найденное ранее значение $R = a \cot(\phi)$, получаем:

$S = \frac{3\sqrt{3}}{4}(a \cot(\phi))^2 = \frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$

Ответ: $\frac{3\sqrt{3}}{4}a^2 \cot^2(\phi)$.

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