(1-cos2a)^2 / (1+cos2a)^2 = (2sin^2 a)^2 / (cos^2 a)^2 左边的等于右边我要过程···不懂啊.数学没救了.

(1-cos2a)^2 / (1+cos2a)^2 = (2sin^2 a)^2 / (cos^2 a)^2 左边的等于右边我要过程···不懂啊.数学没救了.
(1-cos2a)^2 / (1+cos2a)^2 = (2sin^2 a)^2 / (cos^2 a)^2 左边的等于右边我要过程···
不懂啊.数学没救了.

(1-cos2a)^2 / (1+cos2a)^2 = (2sin^2 a)^2 / (cos^2 a)^2 左边的等于右边我要过程···不懂啊.数学没救了.
(1-cos2a)^2 / (1+cos2a)^2
=[1-(1-2sin^2 a)]^2 / [1+(2cos^2 a)-1]^2
=[1-1+2sin^2 a]^2 / [1+2cos^2 a-1]^2
=(2sin^2 a)^2 / (2cos^2 a)^2
=(sin^2 a)^2 / (cos^2 a)^2

二倍角先化成一倍角,再进行化简啊
cos2a=(cosa)^2-(sina)^2=1-2(sina)^2=2(cosa)^2-1
(1-cos2a)^2/(1+cos2a)^2
=(1-(1-2(sina)^2)^2/(1+2(cosa)^2-1)
=(2(sina)^2)^2/(2(cosa)^2)^2
=(sina)^4/(cosa)^4
你的右边式子不对啊