y=2sinx*sin(π/3-x)=2sinx*(√3/2cosx-1/2sinx)
=√3sinxcosx-sinx^2
=√3/2sin2x+1/2cos2x-1/2
=sin(2x+π/6)-1/2
sin(2x+π/6)∈[-1,1]
∴y∈[-3/2,1/2]