原式
=sin(x+π/3)+根号3cos(π/3+x)+2sin(x-π/3)
=2sin(x+2π/3)+2sin(x-π/3)
=2sin(π-(x+2π/3))+2sin(x-π/3)
=2sin(π/3-x)+2sin(x-π/3)
=0