Question

求三角恒等变换中一些比较常见的等式 比如：[sinα]^2+[cos(α+30)]^2+sinαcos(α+30)=3/

Answer 1

[sinα]^2-[sinβ]^2=sin（α-β）cos（α+β）

sinαsin(60-α)sin(60+α)=1/4sin(3α)

cosαcos(60-α)cos(60+α)=1/4cos(3α)

tanαtan(60-α)tan(60+α)=tan(3α)