{"common":{"save":0,"post_id":"7934","level":2,"total":10,"point":10,"point_extra":0},"segment":[{"id":"8324","post_id":"7934","mon_id":"1159278","chapter_id":"1159329","question":"<p>Di\u1ec7n t&iacute;ch c\u1ee7a h&igrave;nh v&agrave;nh khuy&ecirc;n n\u1eb1m gi\u1eefa hai \u0111\u01b0\u1eddng tr&ograve;n \u0111\u1ed3ng t&acirc;m c&oacute; b&aacute;n k&iacute;nh l&agrave; 3 m v&agrave; 4 m l&agrave;:<\/p>","options":["<strong>A.<\/strong> <span class=\"math-tex\">$8\\pi$<\/span> m&sup2;","<strong>B.<\/strong> <span class=\"math-tex\">$6\\pi$<\/span> m&sup2;","<strong>C.<\/strong> <span class=\"math-tex\">$4\\pi$<\/span> m&sup2;","<strong>D.<\/strong> <span class=\"math-tex\">$7\\pi$<\/span> m&sup2;"],"correct":"4","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>D.<\/strong>&nbsp;<span class=\"math-tex\">$7\\pi$<\/span>&nbsp;m&sup2;.<\/span><\/p><p>Di\u1ec7n t&iacute;ch c\u1ee7a h&igrave;nh v&agrave;nh khuy&ecirc;n n\u1eb1m gi\u1eefa hai \u0111\u01b0\u1eddng tr&ograve;n \u0111\u1ed3ng t&acirc;m c&oacute; b&aacute;n k&iacute;nh l&agrave; 3 m v&agrave;<br \/>4 m l&agrave;:&nbsp;<span class=\"math-tex\">$S=\\pi(R^2-r^2)=\\pi(4^2-3^2)=7\\pi$<\/span>&nbsp;m&sup2;.<\/p><p>(v\u1edbi R &gt; r).<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-04 01:59:52","option_type":"math","len":0},{"id":"8326","post_id":"7934","mon_id":"1159278","chapter_id":"1159329","question":"<p>S\u1ed1 \u0111o cung c&oacute; \u0111\u1ed9 d&agrave;i 10<span class=\"math-tex\">$\\pi$<\/span>&nbsp;c\u1ee7a \u0111\u01b0\u1eddng tr&ograve;n b&aacute;n k&iacute;nh 25 cm l&agrave;:<\/p>","options":["<strong>A.<\/strong> 42&deg;","<strong>B.<\/strong> 72&deg;","<strong>C.<\/strong> 36&deg;","<strong>D.<\/strong> 54&deg;"],"correct":"2","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>B.<\/strong> 72&deg;.<\/span><\/p><p>S\u1ed1 \u0111o cung c&oacute; \u0111\u1ed9 d&agrave;i 10<span class=\"math-tex\">$\\pi$<\/span>&nbsp;c\u1ee7a \u0111\u01b0\u1eddng tr&ograve;n b&aacute;n k&iacute;nh 25 cm l&agrave;:<\/p><p><span class=\"math-tex\">$l=\\dfrac{\\pi.R.n}{180}$<\/span>&nbsp;&rArr;&nbsp;<span class=\"math-tex\">$n=\\dfrac{l.180}{\\pi.R}$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$n=\\dfrac{10\\pi.180}{\\pi.25}=$<\/span>&nbsp;72&deg;.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-04 02:05:23","option_type":"txt","len":0},{"id":"8328","post_id":"7934","mon_id":"1159278","chapter_id":"1159329","question":"<p>Cho \u0111\u01b0\u1eddng tr&ograve;n (O ; R),&nbsp; \u0111\u1ed9 d&agrave;i&nbsp;<span class=\"math-tex\">$\\stackrel\\frown{AB}$<\/span>&nbsp; l&agrave; <span class=\"math-tex\">$\\dfrac{\\pi R}{4}$<\/span>, s\u0111&nbsp;<span class=\"math-tex\">$\\stackrel\\frown{AB}$<\/span>&nbsp;l&agrave;:<\/p>","options":["<strong>A.<\/strong> 45&deg;","<strong>B.<\/strong> 60&deg;","<strong>C.<\/strong> 135&deg;","<strong>D.<\/strong> 90&deg;"],"correct":"1","level":"2","hint":"","answer":"<p>Ch\u1ecdn&nbsp;<span style=\"color:#16a085;\"><strong>A.<\/strong> 45&deg;.<\/span><\/p><p>G\u1ecdi n&deg; l&agrave; s\u1ed1 \u0111o cung nh\u1ecf AB.<\/p><p>Ta c&oacute;&nbsp;<span class=\"math-tex\">$l=\\dfrac{\\pi.R.n}{180}$<\/span>&nbsp;&rArr;&nbsp;<span class=\"math-tex\">$n=\\dfrac{l.180}{\\pi.R}$<\/span>&nbsp;hay&nbsp;<span class=\"math-tex\">$n=\\dfrac{\\dfrac{\\pi.R}{4}.180}{\\pi.R}=45^0$<\/span>.<\/p><p>V\u1eady&nbsp;s\u0111&nbsp;<span class=\"math-tex\">$\\stackrel\\frown{AB}$<\/span>&nbsp;= 45&deg;.<\/p>","type":"choose","extra_type":"classic","time":"0","user_id":"127","test":"0","date":"2024-11-04 02:13:47","option_type":"txt","len":1}]}