Chú ý: Để đảm bảo quyền lợi và bảo vệ tài khoản của mình
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{"common":{"save":0,"post_id":"7846","level":3,"total":10,"point":10,"point_extra":0},"segment":[{"id":"7864","post_id":"7846","mon_id":"1159278","chapter_id":"1159328","question":"<p>Cho tam giác ABC vuông t\u1ea1i A có <span class=\"math-tex\">$\\cot B=\\dfrac{4}{3}$<\/span>. Khi \u0111ó: <\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\tan C=\\dfrac{4}{3}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\tan C=\\dfrac{3}{4}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$\\cot C=\\dfrac{4}{3}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\cot C=\\dfrac{1}{3}$<\/span>"],"correct":"1","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>A.<\/strong> <span class=\"math-tex\">$\\tan C=\\dfrac{4}{3}$<\/span><\/span><\/p><p>Tam giác ABC vuông t\u1ea1i A có góc B và góc C là hai góc ph\u1ee5 nhau nên tan góc này b\u1eb1ng côtang góc kia.<\/p><p>Mà <span class=\"math-tex\">$\\cot B=\\dfrac{4}{3}$<\/span> nên <span class=\"math-tex\">$\\tan C=\\dfrac{4}{3}$<\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-17 01:16:09","option_type":"math","len":0},{"id":"7866","post_id":"7846","mon_id":"1159278","chapter_id":"1159328","question":"<p>Cho tam giác ABC vuông t\u1ea1i A có <span class=\"math-tex\">$\\sin B=\\dfrac{3}{5}$<\/span>. Khi \u0111ó:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\cos B=\\dfrac{3}{5}$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\cos C=\\dfrac{3}{5}$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$\\sin C=\\dfrac{3}{5}$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\cot C=\\dfrac{3}{5}$<\/span>"],"correct":"2","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>B.<\/strong> <span class=\"math-tex\">$\\cos C=\\dfrac{3}{5}$<\/span><\/span><\/p><p>Tam giác ABC vuông t\u1ea1i A có góc B và góc C là hai góc ph\u1ee5 nhau nên sin góc này b\u1eb1ng côsin góc kia.<\/p><p>Mà <span class=\"math-tex\">$\\sin B=\\dfrac{3}{5}$<\/span> nên <span style=\"color:#16a085;\"><span class=\"math-tex\">$\\cos C=\\dfrac{3}{5}$<\/span><\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-17 01:18:38","option_type":"math","len":0},{"id":"7868","post_id":"7846","mon_id":"1159278","chapter_id":"1159328","question":"<p>Cho <span class=\"math-tex\">$\\Delta$<\/span>OPQ có OP = 7,2 cm, OQ = 9,6 cm, PQ = 12 cm. S\u1ed1 \u0111o các góc c\u1ee7a <span class=\"math-tex\">$\\Delta$<\/span>OPQ l\u1ea7n l\u01b0\u1ee3t là? (làm tròn k\u1ebft qu\u1ea3 \u0111\u1ebfn \u0111\u1ed9).<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\widehat{P}=37^0;\\widehat{Q}=90^0;\\widehat{O}=53^0$<\/span>","<strong>B.<\/strong> <span class=\"math-tex\">$\\widehat{P}=37^0;\\widehat{Q}=53^0;\\widehat{O}=90^0$<\/span>","<strong>C.<\/strong> <span class=\"math-tex\">$\\widehat{P}=90^0;\\widehat{Q}=37^0;\\widehat{O}=53^0$<\/span>","<strong>D.<\/strong> <span class=\"math-tex\">$\\widehat{P}=53^0;\\widehat{Q}=37^0;\\widehat{O}=90^0$<\/span>"],"correct":"4","level":"3","hint":"","answer":"<p>Ch\u1ecdn <span style=\"color:#16a085;\"><strong>D.<\/strong> <span class=\"math-tex\">$\\widehat{P}=53^0;\\widehat{Q}=37^0;\\widehat{O}=90^0$<\/span><\/span><\/p><p>Ta có: <span class=\"math-tex\">$OP^2+OQ^2=7,2^2+9,6^2=144$<\/span>; <span class=\"math-tex\">$PQ^2=12^2=144$<\/span><\/p><p>Suy ra <span class=\"math-tex\">$OP^2+OQ^2=PQ^2$<\/span> nên <span class=\"math-tex\">$\\Delta$<\/span>OPQ vuông t\u1ea1i O (\u0111\u1ecbnh lí Pythagore \u0111\u1ea3o).<\/p><p>Do \u0111ó <span style=\"color:#16a085;\"><span class=\"math-tex\">$\\widehat{O}=90^0$<\/span><\/span>.<\/p><p><span class=\"svgedit\"><svg height=\"170\" width=\"140\"> <g><title><\/title><rect fill=\"#fff\" height=\"172\" id=\"canvas_background\" width=\"142\" 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><path d=\"m32.56932,145.28965l0,-128l81,128l-81,0z\" fill=\"#56ffaa\" id=\"svg_1\" stroke=\"#000\" stroke-width=\"1.5\"><\/path> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_2\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"116.86363\" xml:space=\"preserve\" y=\"160.43181\">P<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_3\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"10.86363\" xml:space=\"preserve\" y=\"159.43181\">O<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"24\" id=\"svg_4\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"9.86363\" xml:space=\"preserve\" y=\"23.43181\">Q<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_5\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"76.86363\" xml:space=\"preserve\" y=\"79.43181\">12<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_6\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"4.86363\" xml:space=\"preserve\" y=\"94.43181\">9,6<\/text> <text fill=\"#000000\" font-family=\"Helvetica, Arial, sans-serif\" font-size=\"17\" id=\"svg_7\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"0\" text-anchor=\"start\" x=\"56.86363\" xml:space=\"preserve\" y=\"164.43181\">7,2<\/text> <rect fill=\"#56ffaa\" height=\"12\" id=\"svg_8\" stroke=\"#000\" stroke-opacity=\"null\" stroke-width=\"1.5\" width=\"12\" x=\"32.86363\" y=\"133.43181\"><\/rect> <\/g> <\/svg><\/span><\/p><p>Ta có: <span class=\"math-tex\">$\\sin P=\\dfrac{OQ}{PQ}=\\dfrac{9,6}{12}=0,8$<\/span> suy ra <span style=\"color:#16a085;\"><span class=\"math-tex\">$\\widehat{P}\\approx 53^0$<\/span><\/span>.<\/p><p><span style=\"color:#16a085;\"><span class=\"math-tex\">$\\widehat{Q}=90^0-\\widehat{P}\\approx 37^0$<\/span><\/span><\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-10-17 01:31:24","option_type":"math","len":0}]}