{"common":{"save":0,"post_id":"8783","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"11764","post_id":"8783","mon_id":"1159278","chapter_id":"1159334","question":"<p>H&igrave;nh c\u1ea7u t&acirc;m O b&aacute;n k&iacute;nh 0,4 mm th&igrave;&nbsp;c&oacute; th\u1ec3 t&iacute;ch l&agrave;:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$\\dfrac{32\\pi}{375}\\;mm^3$<\/span>.","<strong>B.<\/strong> <span class=\"math-tex\">$\\dfrac{32\\pi}{325}\\;mm^3$<\/span>.","<strong>C.<\/strong> <span class=\"math-tex\">$\\dfrac{16\\pi}{375}\\;mm^3$<\/span>.","<strong>D.<\/strong> <span class=\"math-tex\">$\\dfrac{16\\pi}{325}\\;mm^3$<\/span>."],"correct":"1","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>A.<\/strong>&nbsp;<span class=\"math-tex\">$\\dfrac{32\\pi}{375}\\;mm^3$<\/span>.<\/span><\/p><p>Th\u1ec3 t&iacute;ch c\u1ee7a h&igrave;nh c\u1ea7u t&acirc;m O b&aacute;n k&iacute;nh R = 0,4 mm l&agrave;:<\/p><p><span class=\"math-tex\">$V=\\dfrac{4}{3}\\pi R^3=\\dfrac{4}{3}.\\pi.0,4^3=\\dfrac{32\\pi}{375}$<\/span>&nbsp;(mm&sup3;).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2025-05-30 10:40:32","option_type":"math","len":0},{"id":"11765","post_id":"8783","mon_id":"1159278","chapter_id":"1159334","question":"<p>M\u1ed9t h&igrave;nh tr\u1ee5 c&oacute; chi\u1ec1u cao b\u1eb1ng 5 m v&agrave; di\u1ec7n t&iacute;ch&nbsp;xung quanh b\u1eb1ng <span class=\"math-tex\">$20\\pi \\;(m^2)$<\/span>. T&iacute;nh th\u1ec3 t&iacute;ch c\u1ee7a h&igrave;nh tr\u1ee5.<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$18\\pi\\;m^3$<\/span>.","<strong>B.<\/strong> <span class=\"math-tex\">$20\\pi\\;m^3$<\/span>.","<strong>C.<\/strong> <span class=\"math-tex\">$10\\pi\\;m^3$<\/span>.","<strong>D.<\/strong> <span class=\"math-tex\">$12\\pi\\;m^3$<\/span>."],"correct":"2","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>B.<\/strong>&nbsp;<span class=\"math-tex\">$20\\pi\\;m^3$<\/span>.<\/span><\/p><p>G\u1ecdi R (R &gt; 0, \u0111\u01a1n v\u1ecb m) l&agrave; b&aacute;n k&iacute;nh \u0111&aacute;y c\u1ee7a h&igrave;nh tr\u1ee5.<\/p><p>V&igrave; di\u1ec7n t&iacute;ch&nbsp;xung quanh c\u1ee7a h&igrave;nh tr\u1ee5&nbsp;b\u1eb1ng <span class=\"math-tex\">$20\\pi \\;(m^2)$<\/span>&nbsp;n&ecirc;n&nbsp;<span class=\"math-tex\">$2\\pi R.5=20\\pi$<\/span>. Suy ra R = 2 (m).<\/p><p>Th\u1ec3 t&iacute;ch c\u1ee7a h&igrave;nh tr\u1ee5 l&agrave;&nbsp;<span class=\"math-tex\">$V=\\pi.2^2.5=20\\pi$<\/span>&nbsp;(m&sup3;).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2025-05-30 10:46:33","option_type":"math","len":0},{"id":"11766","post_id":"8783","mon_id":"1159278","chapter_id":"1159334","question":"<p>M\u1ed9t h&igrave;nh c\u1ea7u c&oacute;&nbsp;di\u1ec7n t&iacute;ch b\u1ec1 m\u1eb7t l&agrave; <span class=\"math-tex\">$324\\pi\\;cm^2$<\/span> th&igrave; th\u1ec3 t&iacute;ch c\u1ee7a h&igrave;nh c\u1ea7u \u0111&oacute; l&agrave;:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$792\\pi\\;cm^3$<\/span>.","<strong>B.<\/strong> <span class=\"math-tex\">$108\\pi\\;cm^3$<\/span>.","<strong>C.<\/strong> <span class=\"math-tex\">$972\\pi\\;cm^3$<\/span>.","<strong>D.<\/strong> <span class=\"math-tex\">$927\\pi\\;cm^3$<\/span>."],"correct":"3","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>C.<\/strong>&nbsp;<span class=\"math-tex\">$972\\pi\\;cm^3$<\/span>.<\/span><\/p><p>G\u1ecdi R (R &gt; 0, \u0111\u01a1n v\u1ecb cm) l&agrave; b&aacute;n k&iacute;nh c\u1ee7a h&igrave;nh c\u1ea7u.<\/p><p>V&igrave; h&igrave;nh c\u1ea7u c&oacute; di\u1ec7n t&iacute;ch b\u1ec1 m\u1eb7t l&agrave; <span class=\"math-tex\">$324\\pi\\;cm^2$<\/span>&nbsp;n&ecirc;n&nbsp;<span class=\"math-tex\">$4\\pi R^2=324\\pi$<\/span>. Suy ra R&sup2; = 81 hay R = 9 (cm).<\/p><p>Th\u1ec3 t&iacute;ch c\u1ee7a h&igrave;nh c\u1ea7u \u0111&oacute;&nbsp;l&agrave;&nbsp;<span class=\"math-tex\">$V=\\dfrac{4}{3}\\pi R^3=\\dfrac{4}{3}\\pi.9^3=972\\pi(cm^3)$<\/span>.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2025-05-30 10:51:24","option_type":"math","len":0}]}