f（x）=2cos^2(π/4-x)+sin(2x+π/3)-1
=1+cos(π/2-2x)+1/2sin2x+√3/2cos2x-1
=sin2x+1/2sin2x+√3/2cos2x
=3/2sin2x+√3/2cos2x
=√3sin(2x+π/6)
t=2π/2=π
x在[0,π/2]
2x+π/6在[π/6,7π/6]
函数f（x）的值域[－√3/2,√3]