f(x)=2cosxcosπ/3+2sinxsinπ/3+2cos(π/2-3π/2-x)=cosx+根3sinx+2cos(π+x)=根3sinx-cosx=2(根3/2sinx-1/2cosx)=2(cosπ/6sinx-sinπ/6cosx)=2sin(x-π/6)