f(x)=3sinx^2+2根号3sinxcosx+5cosx^2=3* （1-cos2x）/2+根号3sin2x+5* （1+cos2x）/2=3/2-3/2cos2x+根号3sin2x+5/2+5/2cos2x=4+cos2x+根号3sin2x=4+2sin（2x+π/6）T=2π/2=π最大值=6f(a)=5,即sin（2x+π/6）=1/2...