y=sinx*cosx+1=1/2*2*sinx*cosx+1=1/2sin2x+1
sin2x e [-1,1]
1/2sin2x e [-1/2.1/2]
(1/2sin2x+1) e [1/2., 1 1/2]
y=sinx*cosx+1=1/2*2*sinx*cosx+1=1/2sin2x+1
sin2x e [-1,1]
1/2sin2x e [-1/2.1/2]
(1/2sin2x+1) e [1/2., 1 1/2]