化简sin(x-45)sin(x+45)/(sin^4x-cos^4x)

分类: 作业答案 • 2022-01-09 18:05:45

问题描述：

答

sin(x-45)sin(x+45)/(sin^4x-cos^4x)
=sin(x-45)cos(x+45-90)/(sin^2x-cos^2x)(sin^2x+cos^2x)
=sin(2x-90)/2(-cos2x)
=-cos2x/-2cos2x
=-1/2