灵鹊做题网(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
来源：学生作业帮 编辑：灵鹊做题网作业帮 分类：数学作业 时间：2024/04/19 02:55:45
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)
=(cosπ/12 - sinπ/12)(sinπ/12 + cosπ/12)
=cos²(π/12) - sin²(π/12)
=cos(π/6)
=(根号3)/2
再问： (sin5π/12-sinπ/12)(cos5π/12+cosπ/12)怎么会变成（cosπ/12 - sinπ/12)(sinπ/12 + cosπ/12）
再答： 公式：sin(π/2 - α)=cosα，cos(π/2 - α)=sinα
=(cosπ/12 - sinπ/12)(sinπ/12 + cosπ/12)
=cos²(π/12) - sin²(π/12)
=cos(π/6)
=(根号3)/2
再问： (sin5π/12-sinπ/12)(cos5π/12+cosπ/12)怎么会变成（cosπ/12 - sinπ/12)(sinπ/12 + cosπ/12）
再答： 公式：sin(π/2 - α)=cosα，cos(π/2 - α)=sinα
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
(sin5π/12+cos5π/12)(sinπ/12-cosπ/12)
sin5/12π×cos5/12π怎么算?
cos5π/12=sinπ/12
cos5/12πcosπ/12+cosπ/12sinπ/6=?
(sin5π12−sinπ12)(sin5π12+sinπ12)
数学极限的运算lim α→π/2 （sinα-sin5α）/（cosα+cos5α）
不查表求值：cos5π/12·sinπ/12=
sin5/12π*cosπ/12 怎么算
为什么cos5π/12等于sinπ/12
已知角α终边上一点坐标为(sin5π/6,cos5π/6)求sinα和cosα的值
帮我解,证明恒等式（cos平方5π/12）+（cos平方π/12）+（cos5π/12）（cosπ/12）=5/4