sin(1-2x)=-sin(2x-1) ,是,周期T=2π/2=π
sin²x =(1-cos2x)/2,是,周期T=2π/2=π
3-Isin4xI ,是,周期T=2π/(4×2)=π/4
xcosx ,不是
2cos(x/2)-3sin(x/3),是是,周期T=12π