cos^4 x-sin^4 x+2 sin^2 x化简

问题描述:

cos^4 x-sin^4 x+2 sin^2 x化简

cos^4 x-sin^4 x+2 sin^2 x
=(cos²x+sin²x)(cos²x-sin²x)+2sin² x
=cos²x-sin²x+2sin² x
=cos²x+sin²x
=1