令t=2x-π/3,则π/3<=t<=7π/6.y=2sint
如果利用数形结合很容易看出,最大值在t=π/2处取得,yMAX=2；最小值在t=7π/6处取得,yMIN=2sin(7π/6)=2*(-1/2)=-1.【事实上,该函数在[π/3,π/2]上递增,在[π/2,7π/6]上递减】.
所以：值域是[-1,2].