y=2*(1/2)[cos(2x)-sin(π/2)]+√3sin2x
=cos2x+√3sin2x-1
=2sin(2x+30°)-1.
所以最小正周期为2π/2=π.
因为：
-1<=sin(2x+30°)<=1
-2<2sin(2x+30°)<=2
-3<2sin(2x+30°)-1<=1
所以值域为.[-3,1].