我基本不鼓励玩几何。基本就是凑条件。不符合数学研究发展的规律。

CE/GD = CB/DB -- (1)

CB/CD = AB/CA  => CA/CD = AB/CB -- (2)

 

AF/CA = GD/CD => AF/GD = CA/GD with (2) => AF/GD = AB/CB  --(3)

Now since CB/AB = DB/CB => CB/DB = AB/CB with (3) => AF/GD = CB/DB = CE/GD (from 1)

 

so AF = CE