因为 sin(x-π/4)=sin[π/2-(x+π/4)]=cos(x+π/4)所以 f(x)=2sin(x+π/4)sin(x-π/4)+sin2x=2sin(x+π/4)cos(x+π/4)+sin2x=sin(2x+π/2)+sin2x=cos2x+sin2x=√2[(√2/2)sin2x+(√2/2)cos2x]=√2sin(2x+π/4)所以 ...