y=√3cos²x+1/2sin2x=√3/2(cos2x+1)+1/2sin2x=√3/2cos2x+1/2sin2x+√3/2=sin(π/3)cos2x+cos(π/3)sin2x+√3/2 .//注：sin(π/3)=√3/2,cos(π/3)=1/2=sin(2x+π/3)+√3/2