Hình thang cân - Bài tập nâng cao

Home Lớp 8 Toán lớp 8 - Sách Kết nối tri thức Bài 11. Hình thang cânBài tập nâng cao

{"common":{"save":0,"post_id":"6617","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6040","post_id":"6617","mon_id":"1158921","chapter_id":"1158929","question":"Hình thang ABCD (AB \/\/ CD) có $\\widehat{A}-\\widehat{D}$<\/span> = 30° . S\u1ed1 \u0111o các góc A và góc D c\u1ee7a hình thang l\u1ea7n l\u01b0\u1ee3t là<\/p>","options":["A.<\/strong> 105° và 75°.","B.<\/strong> 75° và 105°.","C.<\/strong> 70° và 110°.","D.<\/strong> 110° và 70°."],"correct":"1","level":"3","hint":"","answer":"<svg height=\"130\" width=\"230\"> <g> <title><\/title> <rect fill=\"#fff\" height=\"132\" id=\"canvas_background\" width=\"232\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" height=\"100%\" id=\"canvasGrid\" overflow=\"visible\" width=\"100%\" x=\"0\" y=\"0\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g> <title><\/title> <g id=\"svg_6\"> <path d=\"m17.01377,118.39512l57.5,-97.00001l105.00001,0l31.49998,96.00001l-167.99999,1z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_2\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"63.31535\" xml:space=\"preserve\" y=\"17.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_3\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"179.31535\" xml:space=\"preserve\" y=\"18.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"213.31535\" xml:space=\"preserve\" y=\"126.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"1.31535\" xml:space=\"preserve\" y=\"127.52273\">D<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Vì AB \/\/ CD  nên  $\\widehat{A}+\\widehat{D}$<\/span> = 180° (hai góc trong cùng phía).<\/p>⇒ $\\widehat{A}=180^0-\\widehat{D}$<\/span> .<\/p>M\u1eb7t khác, $\\widehat{A}-\\widehat{D}$<\/span> = 30°<\/p>    180° – $\\widehat{D}$<\/span> – $\\widehat{D}$<\/span> = 30°<\/p>         180° – 2.$\\widehat{D}$<\/span> = 30°<\/p>                  – 2.$\\widehat{D}$<\/span> = 30° – 180°<\/p>                  – 2.$\\widehat{D}$<\/span> = – 150°<\/p>                        $\\widehat{D}$<\/span> = – 150° : (–2)<\/p>                        $\\widehat{D}$<\/span> = 75°<\/p>Suy ra  $\\widehat{A}=180^0-\\widehat{D}$<\/span> = 180° – 75° = 105°.<\/p>V\u1eady  $\\widehat{A}=105^0 ; \\widehat{D}=75^0$<\/span> .<\/p>\u0110áp án \u0111úng là   A.<\/strong> 105°  và  75°.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-25 00:41:05","option_type":"txt","len":2},{"id":"6042","post_id":"6617","mon_id":"1158921","chapter_id":"1158929","question":"Cho hình thang ABCD (AB \/\/ CD) có $\\widehat{B}-\\widehat{C}=40^0$<\/span> . S\u1ed1 \u0111o các góc B và góc C l\u1ea7n l\u01b0\u1ee3t là <\/p>","options":["A.<\/strong> 105° và 75°.","B.<\/strong> 75° và 105°.","C.<\/strong> 70° và 110°.","D.<\/strong> 110° và 70°."],"correct":"4","level":"3","hint":"","answer":"<svg height=\"130\" width=\"230\"> <g> <title><\/title> <rect fill=\"#fff\" height=\"132\" id=\"canvas_background\" width=\"232\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" height=\"100%\" id=\"canvasGrid\" overflow=\"visible\" width=\"100%\" x=\"0\" y=\"0\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g> <title><\/title> <g id=\"svg_6\"> <path d=\"m17.01377,118.39512l57.5,-97.00001l105.00001,0l31.49998,96.00001l-167.99999,1z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_2\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"63.31535\" xml:space=\"preserve\" y=\"17.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_3\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"179.31535\" xml:space=\"preserve\" y=\"18.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"213.31535\" xml:space=\"preserve\" y=\"126.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"1.31535\" xml:space=\"preserve\" y=\"127.52273\">D<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Vì AB \/\/ CD  nên  $\\widehat{B}+\\widehat{C}$<\/span> = 180° (hai góc trong cùng phía).<\/p>⇒ $\\widehat{B}=180^0-\\widehat{C}$<\/span> .<\/p>M\u1eb7t khác, $\\widehat{B}-\\widehat{C}$<\/span> = 40°<\/p>    180° – $\\widehat{C}$<\/span> – $\\widehat{C}$<\/span> = 40°<\/p>         180° – 2.$\\widehat{C}$<\/span> = 40°<\/p>                  – 2.$\\widehat{C}$<\/span> = 40° – 180°<\/p>                  – 2.$\\widehat{C}$<\/span> = – 140°<\/p>                        $\\widehat{C}$<\/span> = – 140° : (–2)<\/p>                        $\\widehat{C}$<\/span> = 70°<\/p>Suy ra  $\\widehat{B}=180^0-\\widehat{C}$<\/span> = 180° – 70° = 110°.<\/p>V\u1eady  $\\widehat{B}=110^0 ; \\widehat{C}=70^0$<\/span> .<\/p>\u0110áp án \u0111úng là   D.<\/strong> 110° và 70°.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-25 00:43:12","option_type":"txt","len":2},{"id":"6044","post_id":"6617","mon_id":"1158921","chapter_id":"1158929","question":"Cho hình thang ABCD (AB \/\/ CD)  có $\\widehat{A}=2\\widehat{D}$<\/span> . S\u1ed1 \u0111o các góc A và góc D c\u1ee7a hình thang l\u1ea7n l\u01b0\u1ee3t là<\/p>","options":["A.<\/strong> 100° và 50°.","B.<\/strong> 120° và 60°.","C.<\/strong> 110° và 55°.","D.<\/strong> 130° và 65°."],"correct":"2","level":"3","hint":"","answer":"<svg height=\"130\" width=\"230\"> <g> <title><\/title> <rect fill=\"#fff\" height=\"132\" id=\"canvas_background\" width=\"232\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" height=\"100%\" id=\"canvasGrid\" overflow=\"visible\" width=\"100%\" x=\"0\" y=\"0\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g> <title><\/title> <g id=\"svg_6\"> <path d=\"m17.01377,118.39512l57.5,-97.00001l105.00001,0l31.49998,96.00001l-167.99999,1z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_2\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"63.31535\" xml:space=\"preserve\" y=\"17.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_3\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"179.31535\" xml:space=\"preserve\" y=\"18.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"213.31535\" xml:space=\"preserve\" y=\"126.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"1.31535\" xml:space=\"preserve\" y=\"127.52273\">D<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Vì AB \/\/ CD  nên  $\\widehat{A}+\\widehat{D}$<\/span> = 180° (hai góc trong cùng phía).<\/p>                          $2\\widehat{D}+\\widehat{D}$<\/span> = 180°   (vì  $\\widehat{A}=2\\widehat{D}$<\/span> )<\/p>                                 3.$\\widehat{D}$<\/span> = 180°<\/p>                                    $\\widehat{D}$<\/span> = 180° : 3<\/p>                                    $\\widehat{D}$<\/span> = 60°<\/p>Suy ra  $\\widehat{A}=2.\\widehat{D}$<\/span> = 2 . 60° = 120°.<\/p>V\u1eady  $\\widehat{A}=120^0 ; \\widehat{D}=60^0$<\/span> .<\/p>\u0110áp án \u0111úng là   B.<\/strong> 120° và 60°.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-07-25 00:48:47","option_type":"txt","len":2}]}