原式=sinxcosπ/3+cosxsinπ/3+2sinxcosπ/3-2cosxsinπ/3-√3cosxcos2π/3-√3sinxsin2π/3
=1/2*sinx+√3/2*cosx+sinx-√3cosx+√3/2*cosx-3/2*sinx
=0