2sin(x-4/π）sin(x+4/π）

分类: 作业答案 • 2023-01-23 19:12:54

问题描述：

答

=2sin(x-π/4)cos[π/2-(x+π/4)]
=2sin(x-π/4)cos(π/4-x)
=2sin(x-π/4)cos(x-π/4)
=2sin[2(x-π/4)]
=2sin(2x-π/2)
=-2cos2x