{"article_info":{"article_id":140183,"cat_id":1391,"cat_title":"SGK Toán 8 - Chân trời sáng tạo","publish_time":1685689200,"cat_id2":1391,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0602/resize_1-0_7.png","title":"Giải bài 6 trang 72 SGK Toán 8 – Chân trời sáng tạo","label":"Giải bài 6 trang 72","alias":"giai-bai-6-trang-72-sgk-toan-8-chan-troi-sang-tao","introtext":"Cho hình thang cân ","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 hình thang cân <span class=\"MTConvertedEquation\">\\(ABCD\\)</span> có <span class=\"MTConvertedEquation\">\\(AB\\)</span> // <span class=\"MTConvertedEquation\">\\(CD\\)</span>. Qua giao điểm <span class=\"MTConvertedEquation\">\\(E\\)</span> của <span class=\"MTConvertedEquation\">\\(AC\\)</span> và <span class=\"MTConvertedEquation\">\\(BD\\)</span>, ta vẽ đường thẳng song song với <span class=\"MTConvertedEquation\">\\(AB\\)</span> và cắt <span class=\"MTConvertedEquation\">\\(AD\\)</span>, <span class=\"MTConvertedEquation\">\\(BC\\)</span> lần lượt tại <span class=\"MTConvertedEquation\">\\(F\\)</span> và <span class=\"MTConvertedEquation\">\\(G\\)</span> (Hình 16). Chứng minh rằng <span class=\"MTConvertedEquation\">\\(EG\\)</span> là tia phân giác của góc <span class=\"MTConvertedEquation\">\\(CEB\\)</span>.</p>\r\n<p><img src=\"https://img.loigiaihay.com/picture/2023/0602/1_18.png\" /></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>Chứng minh <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{CEG}}} = \\widehat {{\\rm{BEG}}}\\)</span></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>Vì <span class=\"MTConvertedEquation\">\\(EG\\)</span> // <span class=\"MTConvertedEquation\">\\(AB\\)</span> (gt)</p>\r\n<p>suy ra <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{CEG}}} = \\widehat {{\\rm{CAB}}}\\)</span> (đồng vị) và <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{GEB}}} = \\widehat {{\\rm{EBA}}}\\)</span> (so le trong) (1)</p>\r\n<p>Xét <span class=\"MTConvertedEquation\">\\(\\Delta CAB\\)</span> và <span class=\"MTConvertedEquation\">\\(\\Delta DBA\\)</span> ta có:</p>\r\n<p><span class=\"MTConvertedEquation\">\\(AC = BD\\)</span> (tính chất hình thang cân)</p>\r\n<p><span class=\"MTConvertedEquation\">\\(BC = AD\\)</span> (tính chất hình thang cân)</p>\r\n<p><span class=\"MTConvertedEquation\">\\(AB\\)</span> chung</p>\r\n<p>Suy ra <span class=\"MTConvertedEquation\">\\(\\Delta CAB = \\Delta DBA\\)</span> (c-c-c)</p>\r\n<p>Suy ra <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{CAB}}} = \\widehat {{\\rm{EBA}}}\\)</span> (hai góc tương ứng) (2)</p>\r\n<p>Từ (1) và (2) suy ra <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{CEG}}} = \\widehat {{\\rm{GEB}}}\\)</span></p>\r\n<p>Suy ra <span class=\"MTConvertedEquation\">\\(EG\\)</span> là phân giác của <span class=\"MTConvertedEquation\">\\(\\widehat {{\\rm{CEB}}}\\)</span></p>","common_article":"","display_type":1,"vungoi_exam_id":"","article_type":1,"cmt_count":0,"zip_status":1,"last_modified_time":1729819445,"last_zip_time":1729819445,"zip_link":"https://offline.loigiaihay.com/articles/1391/140183/140183_1729819445.zip","picture":"https://img.loigiaihay.com/picture/article/2023/0602/1-0_7.png","youtube_id":"BO2tdBgNuxk","video_start_time":"4270","quizlet_id":"0","ref_article_id":0,"readmore_display_type":0,"wiki":0,"comment_url":"https://loigiaihay.com/comment/giai-bai-6-trang-72-sgk-toan-8-chan-troi-sang-tao-c1391a140183.html","origin_url":"https://loigiaihay.com/giai-bai-6-trang-72-sgk-toan-8-chan-troi-sang-tao-c1391a140183.html","relate_link":[],"exam_file":"","solution_file":""},"callouts":[],"relate_articles":[],"others_in_cat":[{"article_id":140184,"cat_id":1391,"publish_time":1685689380,"is_link":0,"thumbnail":"https://img.loigiaihay.com/picture/article/2023/0602/resize_1-0_8.png","title":"Giải bài 7 trang 72 SGK Toán 8 – 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