问题标题：
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
问题描述：
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)=?
单汨源回答：
(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
田新华回答：
(sin5π/12-sinπ/12)(cos5π/12+cosπ/12)怎么会变成（cosπ/12-sinπ/12)(sinπ/12+cosπ/12）
单汨源回答：
公式：sin(π/2-α)=cosα，cos(π/2-α)=sinα
点击显示
数学推荐
热门数学推荐