化简(1+sin4X-cos4X)÷(1+ sin4X+cos4X)

问题描述:

化简(1+sin4X-cos4X)÷(1+ sin4X+cos4X)

(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...再问一下,sin(x+β+x)怎么化成sin(x+β)cosx-cos(x+β)sinx?这个化不成,你前面一项拆开是sin(x+β+x)=sin[(x+β)+x]=sin(x+β)cosx+cos(x+β)sinx后面一项sinβ=sin(x+β-x)=sin[(x+β)-x]=sin(x+β)cosx-cos(x+β)sinx