f(x)=2√3cos^2(x/2)+2sin(x/2)cos(x/2)+√3 =√3(cosx+1)+sinx+√3 =√3cosx+sinx+2√3 =2sin(x+π/3)+2√3T=2π ,最大值y=2+2√3, 最小值y=2√3-2
