tan(60°-α)tan(30°+α)
问题描述：
tan(60°-α)tan(30°+α)
怎么算成1?
答
tan(60°-α)tan(30°+α)
=tan(60°-α)cot[90°-(30°+α)]
=tan(60°-α)cot(60°-α)
=tan(60°-α)×1/tan(60°-α)
=1