化简(sinxsin3x)/(cosxcos3x)

化简(sinxsin3x)/(cosxcos3x)最后等于tan2x,求具体详细的化简步骤.

1个回答

(sinx+sin3x)/(cosx+cos3x)
=[2sin(x+3x)/2*cos(x-3x)/2]/(2cos(x+3x)/2*cos(x-3x)/2)
=sin2xcosx/cos2xcosx
=tan2x