dtdh.net
当前位置:首页 >> sin15 >>

sin15

sin15=sin(45-30) =sin45cos30-sin30dos45 =√2/2×√3/2-1/2×√2/2 =√6/4-√2/4 =(√6-√2)/4 应该选C吧

sin15º =sin(45º-30º) =sin45ºcos30º-cos45ºsin30º =√2/2*√3/2-√2/2*1/2 =(√6-√2)/4

同理: cos15° =cos(45°-30°) =cos45°cos30°+sin45°sin30° =(√2/2)(√3/2)+(√2/2)(1/2) =(√6+√2)/4

sin15°=(45°-30°)=sin45°cos30°-cos45°sin30°=(6^0.5-2^0.5)/4=(根号6-根号2)/4 你也可以用其他三角函数公式求解!

sin15° =sin(60°-45°) =sin60°cos45°-cos60°sin45°  =√6/4-√2/4 =(√6-√2)/4

4分之(根号6-根号2)

1、本题可以利用诱导公式、辅助角公式或二倍角公式与两角和与差公式求解。 2、解法1:sin15°+sin75°=sin15°+cos15°=√2sin(45°+15°)=√2sin60°=√6/2. 解法2:原式=sin15°+cos15°=√(sin15°+cos15°)²=√(1+sin30°)=√(3/2)=√6/2. 解法3:原式=sin...

sin15° =sin(45°-30°) =sin45°cos30°-cos45°sin30° =√2/2×√3/2-√2/2×1/2 =(√6-√2)/4

如果学过和差化积公式: sin15°+sin75° =2sin[(15°+75°)/2]cos[(15°-75°)/2] =2sin45°cos(-60°) =2sin45°cos60° =2×(√2/2)×(1/2) =√2/2

sin15°=sin(45° - 30°) =sin45°cos30° - cos45°sin30° =√2/2 * √3/2 - √2/2 * 1/2 =(√6 - √2)/4 cos15°=cos(45° - 30°) =cos45°cos30°+sin45°sin30° =√2/2 * √3/2+√2/2 * 1/2 =(√6+√2)/4 tan15°=sin15°/cos15° =[(√6-√2)/4] / [(√6+√2)/4] =(√6-...

网站首页 | 网站地图
All rights reserved Powered by www.dtdh.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com