Bài tập cuối chương 4 - Bài tập trung bình

Home Lớp 8 Toán lớp 8 - Sách Kết nối tri thức Bài tập cuối chương 4Bài tập trung bình

{"common":{"save":0,"post_id":"6587","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"6270","post_id":"6587","mon_id":"1158921","chapter_id":"1158932","question":"Tính \u0111\u1ed9 dài CD trên hình .<\/p><svg height=\"180\" width=\"260\"> <g><title><\/title><rect fill=\"#fff\" height=\"182\" id=\"canvas_background\" width=\"262\" 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_14\"> <g id=\"svg_3\"> <path d=\"m23.10377,149.82699l118.50001,-122l90.5,123l-182.00001,0z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_2\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"141.31535\" x2=\"131.31535\" y1=\"29.52273\" y2=\"149.52273\"><\/line> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-40 128.6463165283203,50.70454406738282) \" x=\"125.31535\" xml:space=\"preserve\" y=\"57.52273\">(<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-106 147.6463165283203,55.704547882080064) \" x=\"144.31535\" xml:space=\"preserve\" y=\"62.52273\">(<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"132.31535\" xml:space=\"preserve\" y=\"25.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"7.31535\" xml:space=\"preserve\" y=\"161.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"124.31535\" xml:space=\"preserve\" y=\"168.52273\">D<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"236.31535\" xml:space=\"preserve\" y=\"162.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"35.31535\" xml:space=\"preserve\" y=\"88.52273\">8 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"58.31535\" xml:space=\"preserve\" y=\"143.52273\">7,2 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"20\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"195.31535\" xml:space=\"preserve\" y=\"96.52273\">6 cm<\/text> <\/g> <\/g> <\/svg><\/span><\/p>","options":["A.<\/strong> 4,5 cm","B.<\/strong> 5,4 cm","C.<\/strong> 12 cm","D.<\/strong> 10 cm"],"correct":"2","level":"2","hint":"","answer":"Trong tam giác ABC có AD là tia phân giác c\u1ee7a góc BAC nên theo \u0111\u1ecbnh lí \u0111\u01b0\u1eddng phân giác, ta có<\/p>$\\dfrac{BD}{CD}=\\dfrac{AB}{AC}$<\/span> suy ra $CD = \\dfrac{BD.AC}{AB}$<\/span> = $\\dfrac{7,2.6}{8}$<\/span> = 5,4 cm.<\/p>\u0110áp án \u0111úng là   B.<\/strong> 5,4 cm.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-09 14:45:15","option_type":"txt","len":0},{"id":"6274","post_id":"6587","mon_id":"1158921","chapter_id":"1158932","question":"Tính c\u1ea1nh AB trên hình.<\/p><svg height=\"200\" width=\"240\"> <g><title><\/title><rect fill=\"#fff\" height=\"202\" id=\"canvas_background\" width=\"242\" 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_14\"> <g id=\"svg_4\"> <path d=\"m15.06377,170.51824l121,-143l88,144l-176,-1z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_3\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"223.31535\" x2=\"80.31535\" y1=\"171.52273\" y2=\"94.52273\"><\/line> <\/g> <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=\"128.31535\" xml:space=\"preserve\" y=\"23.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"225.31535\" xml:space=\"preserve\" y=\"183.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"3.31535\" xml:space=\"preserve\" y=\"187.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"63.31535\" xml:space=\"preserve\" y=\"94.52273\">D<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-48 97.32529449462892,51.1590919494629) \" x=\"70.31535\" xml:space=\"preserve\" y=\"57.52273\">7,6 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-50 30.325286865234375,128.15908813476562) \" x=\"3.31535\" xml:space=\"preserve\" y=\"134.52273\">9,5 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"88.31535\" xml:space=\"preserve\" y=\"190.52273\">10 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(38 200.4971618652344,147.1590881347656) \" x=\"197.31535\" xml:space=\"preserve\" y=\"153.52273\">(<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_13\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"182.31535\" xml:space=\"preserve\" y=\"165.52273\">(<\/text> <\/g> <\/g> <\/svg><\/span><\/p>","options":["A.<\/strong> 8 cm","B.<\/strong> 5 cm","C.<\/strong> 7 cm","D.<\/strong> 6 cm"],"correct":"1","level":"2","hint":"","answer":"Trong tam giác ABC có BD là tia phân giác c\u1ee7a góc ABC nên theo \u0111\u1ecbnh lí \u0111\u01b0\u1eddng phân giác, ta có<\/p>$\\dfrac{AD}{DC}=\\dfrac{AB}{BC}$<\/span> suy ra AB = $\\dfrac{AD.BC}{DC}$<\/span> = $\\dfrac{7,6 . 10}{9,5}$<\/span> = 8 cm.<\/p>\u0110áp án \u0111úng là   A.<\/strong> 8 cm.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-09 15:01:44","option_type":"txt","len":0},{"id":"6278","post_id":"6587","mon_id":"1158921","chapter_id":"1158932","question":"Cho tam giác ABC có AB = 6cm; AC = 8 cm; BC = 10 cm. V\u1ebd tia phân giác AD c\u1ee7a góc BAC . Tính BD.<\/p>Làm tròn k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 th\u1eadp phân th\u1ee9 nh\u1ea5t.<\/p>","options":["A.<\/strong> 1,5 cm","B.<\/strong> 5,7 cm","C.<\/strong> 3,4 cm","D.<\/strong> 4,3 cm"],"correct":"4","level":"2","hint":"","answer":"<svg height=\"200\" width=\"250\"> <g> <title><\/title> <rect fill=\"#fff\" height=\"202\" id=\"canvas_background\" width=\"252\" 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_18\"> <g id=\"svg_5\"> <path d=\"m59.06877,200.88012l0,-155l133,155l-133,0z\" fill=\"#fff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\" transform=\"rotate(131 125.5687713623047,123.38011932373047) \"><\/path> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_2\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"110.31535\" x2=\"115.31535\" y1=\"21.52273\" y2=\"122.52273\"><\/line> <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\" transform=\"rotate(-59 101.49716186523438,43.159088134765625) \" x=\"98.31535\" xml:space=\"preserve\" y=\"49.52273\">(<\/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\" transform=\"rotate(-118 117.4971694946289,42.15909194946289) \" x=\"114.31535\" xml:space=\"preserve\" y=\"48.52273\">(<\/text> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"100.31535\" xml:space=\"preserve\" y=\"20.52273\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"10.31535\" xml:space=\"preserve\" y=\"134.52273\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"229.31535\" xml:space=\"preserve\" y=\"136.52273\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"107.31535\" xml:space=\"preserve\" y=\"142.52273\">D<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"26.31535\" xml:space=\"preserve\" y=\"72.52273\">6 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"173.31535\" xml:space=\"preserve\" y=\"67.52273\">8 cm<\/text> <g id=\"svg_15\"> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_12\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"21.31535\" x2=\"226.31535\" y1=\"158.52273\" y2=\"159\"><\/line> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_13\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"18.31535\" xml:space=\"preserve\" y=\"164.52273\"><<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_14\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"219.31535\" xml:space=\"preserve\" y=\"165.52273\">><\/text> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_16\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"94.31535\" xml:space=\"preserve\" y=\"176.52273\">10 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_17\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"67.31535\" xml:space=\"preserve\" y=\"115.52273\">?<\/text> <\/g> <\/g> <\/svg><\/span><\/p>Vì AD là tia phân giác c\u1ee7a góc BAC c\u1ee7a tam giác ABC nên theo \u0111\u1ecbnh lí \u0111\u01b0\u1eddng phân giác, ta có<\/p>$\\dfrac{BD}{DC}=\\dfrac{AB}{AC}$<\/span>  hay  $\\dfrac{BD}{DC}=\\dfrac{6}{8}$<\/span> suy ra $\\dfrac{BD}{6}=\\dfrac{DC}{8}$<\/span> .<\/p>Áp d\u1ee5ng tính ch\u1ea5t c\u1ee7a dãy t\u1ec9 s\u1ed1 b\u1eb1ng nhau,  ta có<\/p>$\\dfrac{BD}{6}=\\dfrac{DC}{8}=\\dfrac{BD+DC}{6+8}=\\dfrac{BC}{14} = \\dfrac{10}{14}$<\/span><\/p>Suy ra $\\dfrac{BD}{6}=\\dfrac{10}{14}$<\/span> do \u0111ó BD = $\\dfrac{6.10}{14}$<\/span> $\\approx$<\/span> 4,3 cm.<\/p>\u0110áp án \u0111úng là   D.<\/strong> 4,3 cm.<\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"131","test":"0","date":"2023-08-09 15:13:29","option_type":"txt","len":0}]}