化简cos²（α-π/4）-sin²（π/4-α）~

化简cos²（α-π/4）-sin²（π/4-α）~
化简cos²（α-π/4）-sin²（π/4-α）~

化简cos²（α-π/4）-sin²（π/4-α）~
答：
cos²(a-π/4)-sin²(π/4-a)
=cos²(a-π/4)-sin²(a-π/4)
=cos(2a-π/2)
=cos(π/2-2a)
=sin2a

cos²(α-π/4)-sin²(π/4-α)
=cos²(π/4-α)-sin²(π/4-α)
=cos2(π/4-α)
=cos(π/2-2α)
=sin2α