Một số hệ thức giữa cạnh, góc trong tam giác vuông và ứng dụng

Home Lớp 9 Toán lớp 9 - Sách Kết nối tri thức Bài 12. Một số hệ thức giữa cạnh, góc trong tam giác vuông và ứng dụngBài tập nâng cao

{"common":{"save":0,"post_id":"7944","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8383","post_id":"7944","mon_id":"1159278","chapter_id":"1159328","question":"Cho $\\triangle$<\/span>ABC vuông t\u1ea1i A có AB = c, BC = a, CA = b. Tia phân giác c\u1ee7a góc B c\u1eaft AC t\u1ea1i D. Tính $\\tan\\dfrac{B}{2}$<\/span>.<\/p>","options":["A.<\/strong> $\\dfrac{a+b}{b-c}$<\/span>","B.<\/strong> $\\dfrac{b}{a-c}$<\/span>","C.<\/strong> $\\dfrac{b}{a+c}$<\/span>","D.<\/strong> $\\dfrac{b}{c-a}$<\/span>"],"correct":"3","level":"3","hint":"","answer":"Ch\u1ecdn C.<\/strong> $\\dfrac{b}{a+c}$<\/span>.<\/span><\/p><svg height=\"200\" width=\"300\"> <g><title><\/title><rect fill=\"#d4ffaa\" height=\"202\" id=\"canvas_background\" width=\"302\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" id=\"canvasGrid\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" id=\"svg_20\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g><title><\/title><g id=\"svg_7\"> <g id=\"svg_3\"> <path d=\"m21.4275,152.15875l0,-136.00001l250,136.00001l-250,0z\" 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=\"21.5\" x2=\"95.5\" y1=\"16.25\" y2=\"152.25\"><\/line> <\/g> <rect fill=\"none\" fill-opacity=\"null\" height=\"12\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"12\" x=\"21.5\" y=\"139.25\"><\/rect> <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\" transform=\"rotate(62 29.5,45.25) \" x=\"26.5\" xml:space=\"preserve\" y=\"51.25\">)<\/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\" transform=\"rotate(26 42.50000000000003,35.24999999999999) \" x=\"39.5\" xml:space=\"preserve\" y=\"41.25\">)<\/text> <\/g> <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=\"4.5\" xml:space=\"preserve\" y=\"163.25\">A<\/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=\"5.5\" xml:space=\"preserve\" y=\"17.25\">B<\/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=\"88.5\" xml:space=\"preserve\" y=\"169.25\">D<\/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=\"274.5\" xml:space=\"preserve\" y=\"160.25\">C<\/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\" x=\"139.5\" xml:space=\"preserve\" y=\"76.25\">a<\/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=\"125.5\" xml:space=\"preserve\" y=\"195.25\">b<\/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=\"3.5\" xml:space=\"preserve\" y=\"86.25\">c<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_15\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"27.5\" xml:space=\"preserve\" y=\"68.25\">1<\/text> <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=\"46.5\" xml:space=\"preserve\" y=\"51.25\">2<\/text> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_17\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" x1=\"20.5\" x2=\"272.5\" y1=\"172.25\" y2=\"172.25\"><\/line> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_18\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"17.5\" xml:space=\"preserve\" y=\"179.25\"><<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"18\" id=\"svg_19\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"265.5\" xml:space=\"preserve\" y=\"179.25\">><\/text> <\/g> <\/svg><\/span><\/p>Ta có: BD là phân giác c\u1ee7a góc B , nên áp d\u1ee5ng tính ch\u1ea5t \u0111\u01b0\u1eddng phân giác ta \u0111\u01b0\u1ee3c:<\/p>$\\dfrac{AD}{DC}=\\dfrac{AB}{BC}=\\dfrac{c}{a}$<\/span> hay $\\dfrac{AD}{DC+AD}=\\dfrac{c}{c+a}$<\/span> suy ra $\\dfrac{AD}{AC}=\\dfrac{c}{c+a}$<\/span> suy ra $AD=\\dfrac{bc}{c+a}$<\/span>.<\/p>Vì $\\triangle$<\/span> ABD vuông t\u1ea1i A nên $\\tan\\dfrac{B}{2}=\\tan B_1=\\dfrac{AD}{AB}=\\dfrac{bc}{(c+a).c}=\\dfrac{b}{c+a}$<\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-06 01:47:11","option_type":"math","len":0},{"id":"8386","post_id":"7944","mon_id":"1159278","chapter_id":"1159328","question":"Cho hình v\u1ebd. Di\u1ec7n tích tam giác OMN (làm tròn \u0111\u1ebfn ch\u1eef s\u1ed1 hàng \u0111\u01a1n v\u1ecb) là<\/p><svg height=\"210\" width=\"260\"> <g><title><\/title><rect fill=\"#ffffff\" height=\"212\" 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_5\"> <path d=\"m29.3325,176.18875l0,-164.00001l208.99999,164.00001l-208.99999,0z\" fill=\"#ffffff\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <line fill=\"#ffffff\" id=\"svg_3\" stroke=\"#000\" stroke-linecap=\"undefined\" stroke-linejoin=\"undefined\" stroke-width=\"1.5\" transform=\"rotate(60 105.49999999999997,144.25) \" x1=\"-45.5\" x2=\"256.5\" y1=\"144.25\" y2=\"144.25\"><\/line> <rect fill=\"#ffffff\" height=\"123\" id=\"svg_4\" stroke-width=\"1.5\" width=\"93\" x=\"116.5\" y=\"177.25\"><\/rect> <\/g> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_6\" stroke-width=\"0\" text-anchor=\"start\" x=\"9.5\" xml:space=\"preserve\" y=\"189.25\">P<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_7\" stroke-width=\"0\" text-anchor=\"start\" x=\"7.5\" xml:space=\"preserve\" y=\"20.25\">O<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_8\" stroke=\"null\" stroke-width=\"0\" style=\"cursor: move;\" text-anchor=\"start\" x=\"113.5\" xml:space=\"preserve\" y=\"197.25\">M<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_9\" stroke-width=\"0\" text-anchor=\"start\" x=\"237.5\" xml:space=\"preserve\" y=\"195.25\">N<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_10\" stroke-width=\"0\" text-anchor=\"start\" x=\"73.5\" xml:space=\"preserve\" y=\"172.25\">60<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_11\" stroke-width=\"0\" text-anchor=\"start\" x=\"173.5\" xml:space=\"preserve\" y=\"174.25\">38<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_12\" stroke-width=\"0\" text-anchor=\"start\" x=\"140.5\" xml:space=\"preserve\" y=\"90.25\">9 cm<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"16\" id=\"svg_13\" stroke-width=\"0\" text-anchor=\"start\" x=\"99.5\" xml:space=\"preserve\" y=\"159.25\">o<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"16\" id=\"svg_14\" stroke-width=\"0\" text-anchor=\"start\" x=\"198.5\" xml:space=\"preserve\" y=\"161.25\">o<\/text> <rect fill=\"none\" height=\"17\" id=\"svg_15\" stroke=\"#000000\" stroke-width=\"1.5\" width=\"17\" x=\"29.5\" y=\"159\"><\/rect> <\/g> <\/svg><\/span><\/p>","options":["A.<\/strong> 7 cm²","B.<\/strong> 8 cm²","C.<\/strong> 9 cm²","D.<\/strong> 11 cm²"],"correct":"4","level":"3","hint":"","answer":"Ch\u1ecdn D.<\/strong> 11 cm².<\/span><\/p>$\\triangle$<\/span> OPN vuông t\u1ea1i P nên ta có:<\/p>$OP = ON.\\sin38^0=9.\\sin38^0\\approx5,54$<\/span> (cm)<\/p>$NP = ON.\\cos38^0=9.\\cos38^0\\approx7,09$<\/span> (cm)<\/p>$\\triangle$<\/span> OPM vuông t\u1ea1i P nên ta có:<\/p>$PM=OP.\\cot60^0=5,54.\\dfrac{1}{\\sqrt{3}}\\approx3,2$<\/span> (cm)<\/p>Khi \u0111ó $MN=NP-PM=7,09-3,2=3,89$<\/span> (cm)<\/p>Di\u1ec7n tích tam giác OMN là<\/p> $S=\\dfrac{1}{2}.OP.MN=\\dfrac{1}{2}.5,54.3,89$<\/span> $\\approx11$<\/span> (cm²).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-06 02:03:26","option_type":"txt","len":1},{"id":"8388","post_id":"7944","mon_id":"1159278","chapter_id":"1159328","question":"Cho $\\triangle$<\/span> ABC là tam giác \u0111\u1ec1u c\u1ea1nh 8cm và $\\widehat{AMB}$<\/span> = 42°. \u0110\u1ed9 dài c\u1ea1nh AM (làm tròn k\u1ebft qu\u1ea3 \u0111\u1ebfn ch\u1eef s\u1ed1 th\u1eadp phân th\u1ee9 hai) là:<\/p><svg height=\"200\" width=\"250\"> <g><title><\/title><rect fill=\"#ffffff\" height=\"202\" id=\"canvas_background\" width=\"252\" x=\"-1\" y=\"-1\"><\/rect> <g display=\"none\" id=\"canvasGrid\"> <rect fill=\"url(#gridpattern)\" height=\"100%\" id=\"svg_16\" stroke-width=\"0\" width=\"100%\" x=\"0\" y=\"0\"><\/rect> <\/g> <\/g> <g><title><\/title><g id=\"svg_4\"> <path d=\"m79.2075,163.23688l72,-140l72,140l-143.99999,0l-0.00001,0z\" 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=\"151.5\" x2=\"21.49999\" y1=\"22.24999\" y2=\"162.24999\"><\/line> <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=\"79.5\" x2=\"20.5\" y1=\"163.25\" y2=\"163\"><\/line> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"141.5\" xml:space=\"preserve\" y=\"22.25\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"-0.5\" xml:space=\"preserve\" y=\"178.25\">M<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"72.5\" xml:space=\"preserve\" y=\"184.25\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"223.5\" xml:space=\"preserve\" y=\"173.25\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"189.5\" xml:space=\"preserve\" y=\"93.25\">8 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"46.5\" xml:space=\"preserve\" y=\"156.25\">42<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"65.5\" xml:space=\"preserve\" y=\"146.25\">o<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-23 39.49999999999996,153.75000000000003) \" x=\"36.5\" xml:space=\"preserve\" y=\"159.25\">)<\/text> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_17\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"98.5\" x2=\"118.5\" y1=\"99.25\" y2=\"112.25\"><\/line> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_18\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"183.5\" x2=\"205.5\" y1=\"112.25\" y2=\"103.25\"><\/line> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_20\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"150.5\" x2=\"151.5\" y1=\"150.25\" y2=\"177.25\"><\/line> <\/g> <\/svg><\/span><\/p>","options":["A.<\/strong> 10,35 cm","B.<\/strong> 10,83 cm","C.<\/strong> 11,05 cm","D.<\/strong> 12,43 cm"],"correct":"1","level":"3","hint":"","answer":"Ch\u1ecdn A.<\/strong> 10,35 cm.<\/span><\/p><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_4\"> <path d=\"m79.2075,163.23688l72,-140l72,140l-143.99999,0z\" 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=\"151.5\" x2=\"21.49999\" y1=\"22.24999\" y2=\"162.24999\"><\/line> <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=\"79.5\" x2=\"20.5\" y1=\"163.25\" y2=\"163\"><\/line> <\/g> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"141.5\" xml:space=\"preserve\" y=\"22.25\">A<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"-0.5\" xml:space=\"preserve\" y=\"178.25\">M<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"72.5\" xml:space=\"preserve\" y=\"184.25\">B<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"223.5\" xml:space=\"preserve\" y=\"173.25\">C<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_9\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"189.5\" xml:space=\"preserve\" y=\"93.25\">8 cm<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_10\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"46.5\" xml:space=\"preserve\" y=\"156.25\">42<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_11\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"65.5\" xml:space=\"preserve\" y=\"146.25\">o<\/text> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_12\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" transform=\"rotate(-23 39.49999999999996,153.75000000000003) \" x=\"36.5\" xml:space=\"preserve\" y=\"159.25\">)<\/text> <line fill=\"none\" fill-opacity=\"null\" id=\"svg_13\" stroke=\"#000\" stroke-linecap=\"null\" stroke-linejoin=\"null\" stroke-opacity=\"null\" stroke-width=\"1.5\" x1=\"151.5\" x2=\"151.5\" y1=\"24.25\" y2=\"164.25\"><\/line> <rect fill=\"none\" fill-opacity=\"null\" height=\"19\" id=\"svg_14\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"19\" x=\"151.5\" y=\"144.25\"><\/rect> <text fill=\"#000000\" fill-opacity=\"null\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_15\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"143.5\" xml:space=\"preserve\" y=\"186.25\">H<\/text> <\/g> <\/svg><\/span><\/p>K\u1ebb \u0111\u01b0\u1eddng cao AH $\\bot$<\/span> BC, H ∈ BC. Do $\\triangle$<\/span>ABC \u0111\u1ec1u nên AH c\u0169ng là \u0111\u01b0\u1eddng trung tuy\u1ebfn suy ra HB = HC = 4 cm. Xét $\\triangle$<\/span>ABH vuông t\u1ea1i H ta có: $AH^2=AB^2-BH^2=8^2-4^2=48$<\/span> hay AH = $4\\sqrt{3}$<\/span> cm. Xét $\\triangle$<\/span>AHM vuông t\u1ea1i H có $AM=AH:\\sin42^0=4\\sqrt{3}:\\sin42^0\\approx10,35$<\/span> cm.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-06 02:14:56","option_type":"txt","len":1}]}