{"article_info":{"article_id":144445,"cat_id":1439,"cat_title":"SGK Toán 8 - Cùng khám phá","publish_time":1690001820,"cat_id2":1439,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0722/resize_1-0_2.png","title":"Giải bài 6.27 trang 61 SGK Toán 8 - Cùng khám phá","label":"Giải bài 6.27 trang 61","alias":"giai-bai-627-trang-61-sgk-toan-8-cung-kham-pha","introtext":"Cho tam giác \\(ABC\\). Trên cạnh \\(BC\\) lấy hai điểm \\(E\\) và \\(F\\) (\\(E\\) nằm giữa \\(B\\)","content":"<style>\r\n.method-close-icon{position: relative;float: right;top: 6px;transform: rotate(270deg);-ms-transform:rotate(270deg);-moz-transform:rotate(270deg);-webkit-transform:rotate(270deg);-o-transform:rotate(270deg);}\r\n.method-open-icon{position: relative;float: right;top: 6px;}\r\n</style>\r\n<p><strong style=\"font-size: 16px;\">Đề bài</strong></p><p>Cho tam giác \\(ABC\\). Trên cạnh \\(BC\\) lấy hai điểm \\(E\\) và \\(F\\) (\\(E\\) nằm giữa \\(B\\)</p>\r\n<p>và \\(F\\)). Đường thẳng qua \\(E\\) song song với \\(AB\\) và đường thẳng qua \\(F\\) song song với \\(AC\\) cắt nhau tại \\(D\\). Chứng minh rẳng tam giác \\(DEF\\) đồng dạng với tam giác \\(ABC\\)</p><div id=\"pos_end_question\"></div><div style=\"padding-top: 10px;padding-bottom: 2px;margin-bottom: 10px;\"><p class=\"show-detail-method\" style=\"background: #654bc2;text-align: center;border-radius:5px;padding: 10px;margin-bottom: 0px;\" onclick=\"showDetailMethod();\"><strong style=\"font-size: 16px;\">Phương pháp giải - Xem chi tiết</strong><img class=\"method-open-icon\" id=\"method_colapse_icon\" src=\"data:image/png;base64,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\"></p>  <div class=\"content_method_content\" style=\"padding: 10px 10px 5px 10px;border: dashed 1px #654bc2;border-top:none;\"><p>Nếu hai góc của tam giác này lần lượt bằng hai góc của tam giác kia thì hai tam giác đó đồng dạng với nhau.</p>  </div>\r\n<script type=\"text/javascript\">\r\n    var is_open =true;\r\n    function showDetailMethod(){\r\n        if(is_open){\r\n            document.querySelector(\".content_method_content\").style.display='none';\r\n            document.getElementById(\"method_colapse_icon\").classList.remove(\"method-open-icon\");\r\n            document.getElementById(\"method_colapse_icon\").classList.add(\"method-close-icon\");\r\n        }else{\r\n            document.querySelector(\".content_method_content\").style.display='block';\r\n            document.getElementById(\"method_colapse_icon\").classList.remove(\"method-close-icon\");\r\n            document.getElementById(\"method_colapse_icon\").classList.add(\"method-open-icon\");\r\n        }\r\n        is_open = !is_open;\r\n    }\r\n</script>\r\n</div><p><strong style=\"font-size: 16px;\">Lời giải chi tiết</strong></p><p><img src=\"https://img.loigiaihay.com/picture/2023/0722/1_6.png\"   /></p>\r\n<p>Ta có:</p>\r\n<p>\\(FD//AC\\) (gt)</p>\r\n<p>=&gt; \\(\\widehat {DFE} = \\widehat {ACB}\\) (hai góc đồng vị tương ứng bằng nhau) (1)</p>\r\n<p>\\(ED//AB\\) (gt)</p>\r\n<p>=&gt; \\(\\widehat {DEF} = \\widehat {ABC}\\) (hai góc đồng vị tương ứng bằng nhau) (2)</p>\r\n<p>Từ (1) và (2) suy ra \\(\\Delta ABC\\) ∽ \\(\\Delta DEF\\) (g-g)</p>","common_article":"","display_type":1,"vungoi_exam_id":"","article_type":1,"cmt_count":0,"zip_status":1,"last_modified_time":1690002143,"last_zip_time":1690002143,"zip_link":"https://offline.loigiaihay.com/articles/1439/144445/144445_1690002143.zip","picture":"https://img.loigiaihay.com/picture/article/2023/0722/1-0_2.png","youtube_id":"","video_start_time":"0","quizlet_id":"0","ref_article_id":0,"readmore_display_type":0,"wiki":0,"comment_url":"https://loigiaihay.com/comment/giai-bai-627-trang-61-sgk-toan-8-cung-kham-pha-c1439a144445.html","origin_url":"https://loigiaihay.com/giai-bai-627-trang-61-sgk-toan-8-cung-kham-pha-c1439a144445.html","relate_link":[],"exam_file":"","solution_file":""},"callouts":[],"relate_articles":[],"others_in_cat":[{"article_id":144446,"cat_id":1439,"publish_time":1690007340,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0722/resize_1-0_3.png","title":"Giải bài 6.28 trang 61 SGK Toán 8 - Cùng khám phá","alias":"giai-bai-628-trang-61-sgk-toan-8-cung-kham-pha","introtext":"Trong Hình 6.75, \\(A\\)là giao điểm của \\(BE\\) và \\(CD\\).","display_type":1,"article_type":1},{"article_id":144448,"cat_id":1439,"publish_time":1690007460,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0722/resize_1-0_4.png","title":"Giải bài 6.29 trang 61 SGK Toán 8 - Cùng khám phá","alias":"giai-bai-629-trang-61-sgk-toan-8-cung-kham-pha","introtext":"Cho tam giác \\(ABC\\) có \\(\\widehat B < \\widehat C\\). ","display_type":1,"article_type":1},{"article_id":144444,"cat_id":1439,"publish_time":1690000860,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0722/resize_1-0_1.png","title":"Giải câu hỏi trang 59, 60 SGK Toán 8 - Cùng khám phá","alias":"giai-cau-hoi-trang-59-60-sgk-toan-8-cung-kham-pha","introtext":"Cắt \\(\\Delta A'B'C'\\) và \\(\\Delta ABC\\) bằng giấy có \\(\\widehat {A'} = \\widehat A\\) và \\(\\widehat {B'} = \\widehat B\\). ","display_type":2,"article_type":1},{"article_id":144191,"cat_id":1439,"publish_time":1689235980,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0713/resize_1-0_8.png","title":"Lý thuyết Trường hợp đồng dạng góc - góc SGK Toán 8 - Cùng khám phá","alias":"ly-thuyet-truong-hop-dong-dang-goc-goc-sgk-toan-8-cung-kham-pha","introtext":"Trường hợp đồng dạng góc - góc là gì?","display_type":0,"article_type":1}],"event_info":{"title":"Bài 7. 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