cos2a-1+2sin^2a

问题描述:

cos2a-1+2sin^2a
怎么化简哦

cos 2a=cos(a+a) =cos a*cos a -sina *sina = (1-sin^2a)- sin^2a =1-2sin^2a
所以 cos2a-1+2sin^2a =1-2sin^2a-1+2sin^2a =0