y=1/2sin2x+4sinx*sinx
=1/2sin2x+4(1-cos2x)/2
=1/2sin2x-2cos2x+2
=√17/2(sin2x*1/√17-cos2x*4/√17)+1
令1/√17=cost,4/√17=sint
=√17/2sin(2x-t)+2
-1≤sin(2x-t)≤1
值域【-√17/2+2,√17/2+2】