化简y=sin^2x+2sinxcosx+3cos^2x
得
y=sin2x+cos2x+2
=根号2(sin2xcosπ/4+cos2xsinπ/4)+2
=根号2sin(2x+π/4)+2
=根号2sin[2(x+π/8)]+2
由函数y=根2*sin2x,x∈R的图像
向左平移π/8单位再向上平移2单位
得出