(1)f(x)=sin^2x-sinxcosx.
=(1-cos2x)/2-(sin2x)/2
=-(cos2x+sin2x)/2+1/2
=-√2sin(2x+π/4)/2+1/2
T=2π/lwl=2π/2=π
最小正周期是π
(2)π/2+2kπ