f(x)=cos平方(x-π/4)-cos平方(x+π/4)的周期急╯_╰

f(x)=cos平方(x-π/4)-cos平方(x+π/4)的周期
急╯_╰

答：
cos(x+π/4)=-sin(x+π/4-π/2)=-sin(x-π/4)
所以f(x)=cos²(x-π/4)-cos²(x+π/4)
=cos²(x-π/4)-sin²(x-π/4)
=cos(2x-π/2)
=-sin2x
T=2π/|w|=2π/2=π
周期是π.