y=sin²x+sinxcosx+2=(1-cos2x)/2+(sin2x)/2+2=(1/2)(sin2x-cos2x)+5/2=(1/2)*√2(sin2xcosπ/4-cos2xsinπ/4)+5/2=(√2/2)sin(2x-π/4)+5/2所以：y的最小值=-(√2/2)+5/2=(5-√2)/2y的最大值=(√2/2)+5/2=(5+√...