帮帮化简sin^4x-cos^4x

分类: 作业答案 • 2022-01-09 18:05:33

问题描述：

帮帮化简sin^4x-cos^4x
(sin^2x+cos^2x )(sin^2x-cos^2x)怎么得sin^2x-cos^2x?麻烦

答

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