（1+sin4X-cos4X)=(sin2x)^2+(cos2x)^2+2sin2xcos2x-(cos2x)^2+(sin2x)^2=2(sin2x)^2+2sin2xcos2x=2sin2x(sin2x+cos2x)（1+ sin4X+cos4X）=(sin2x)^2+(cos2x)^2+2sin2xcos2x+(cos2x)^2-(sin2x)^2=2(cos2x)^2+2sin2xc...再問一下，sin(x+β+x）怎么化成sin(x+β)cosx-cos(x+β)sinx？這個(gè)化不成，你前面一項(xiàng)拆開是sin(x+β+x）=sin[(x+β）+x]=sin(x+β)cosx+cos(x+β)sinx后面一項(xiàng)sinβ=sin(x+β-x)=sin[(x+β)-x]=sin(x+β)cosx-cos(x+β)sinx