Question

为什么sin²(π/4+x)＝cos²(π/4-x)，拍下来吧

Answer 1

如图

Answer 2

[sin(π/4+x)]^2
=[ sinx.cos(π/4) +cosx.sin(π/4) ]^2
=(1/2)( sinx+cosx)^2
[cos(π/4-x)]^2
=[ cosx.cos(π/4) +sinx.sin(π/4) ]^2
=(1/2)( sinx+cosx)^2
=>
[sin(π/4+x)]^2=[cos(π/4-x)]^2