sin(x+π/3)=-√3/3cosx+cos(x-π/3) = 2cos[(x+x-π/3)/2]cos[(x-x+π/3)/2]= 2cos(x-π/6)cos(π/6)= 2cos(π/6-x)cos(π/6)= 2sin[π/2-(π/6-x)]cos(π/6)= 2sin(x+π/3)cos(π/6)= 2×√3/3×√3/2 = 1
