f(x)=cos(2x-π/3)+sin²x-cos^2x
=1/2cos2x+√3/2sin2x-cos2x
=√3/2sin2x-1/2cos2x
=sin(2x-π/6)
f(x)周期T=2π/2=π
对称轴方程 2x-π/6=kπ+π/2 x=kπ/2+π/3
f(x)∈[-1,1]
令f(x)=t
y=t^2+t t∈[-1,1]
=(t+1/2)^2-1/4
当t=1时,ymax=2
当t=-1/2时 ,ymin=-1/4
g（x）值域[-1/4,2]