在选修《数学的感悟》选修课的过程中,听陈老师介绍了“蝴蝶定理”及其两种证法.第一种方法完全利用初中的平面几何知识,但用了7条辅助线,对我来说太难了.第二种方法是1973年美国中学教师斯特温(Steven)给出的面积法,虽然没有辅助线,但也很难想到.能不能探索出属于我自己的方法呢?蝴蝶定理过圆O的弦PQ的中点M引任意两条弦AB与CD,连接AD,BC分别交PQ于E,F两点,求证:ME=MF. In the elective course of “mathematics sentiment”, I listened to Chen’s introduction of “Butterfly Theorem” and its two kinds of proofs. The first method made full use of plane geometry of junior middle school, but used seven auxiliary lines , Which is too hard for me.The second method is the area method given by the American high school teacher, Steven, in 1973, though it is hard to think of without the helpline, can I explore my own Method? Butterfly Theorem O round O of the middle of the string PQ M arbitrary reference to the two strings AB and CD, connecting AD, BC, respectively, to pay PQ at E, F two points, verify: ME = MF.