cos^4x-sin^4x 2sin^2x=

分类: 作业答案 • 2021-12-18 12:05:00

问题描述：

答

cos^4x-sin^4x+2sin^2x
=(cos^2x+sin^2x)(coa^2x-sin^2x)+2sin^2x
=coa^2x-sin^2x+2sin^2x
=cos^2x+sin^2x
=1