求证sin2α/(sinα-cosα)-(sinα+cosα)/(tan2-1)=sinα+cosα
问题描述:
求证sin2α/(sinα-cosα)-(sinα+cosα)/(tan2-1)=sinα+cosα
(1)sin2α/(sinα-cosα)-(sinα+cosα)/(tan2-1)=sinα+cosα(2)(2-cos2α)×(2+tan2α)=(1+2tan2α)×(2-sin2α)
答
(1)sin2α/(sinα-cosα)-(sinα+cosα)/(tan2-1)=sin2α/(sinα-cosα)-cos2α/(sinα-cosα)=(sin2α-cos2α)/(sinα-cosα)=sinα+cosα(2)左边-右边=(1+sin2α)(2+tan2α)-(1+2tan2α)(2-sin2α)=(2...