cosx/2(sinx/2+√3cosx/2)-√3/2
=cosx/2sinx/2+√3cos^2x/2)-√3/2
=1/2sinx+√3/2(1+cosx)-√3/2
=1/2sinx+√3/2cosx
=sin(x+π/3)
对称轴x=Kπ+π/6