f(x)=sin^2(x+派/4)-sin^2(x-派/4)
=(sinxcosπ\4+cosxsinπ\4)^2-(sinxcosπ\4-cosxsinπ\4)^2
=(2sinxcosπ\4)(2cosxsinπ\4)
=4根号2sinxcosx
=2根号2sin2x
是奇函数
T=π