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贵刊《数学通报》2 0 0 4年第 1期刊登了周春荔的《蝴蝶定理》一文 ,笔者联想到中学新教材中的向量知识 ,于是 ,笔者尝试运用向量来证明蝴蝶定理 ,得到了如下的证明方法 ,希望能引起读者的兴趣 .蝴蝶定理 如图 ,M是⊙O的弦EF的中点 ,AC ,BD是过点M的两条弦 ,连接AB ,CD分别交E
In the first issue of Mathematical Bulletin of 2004, No. 1, published by Zhou Chunli’s “butterfly theorem”, the author is reminded of the vector knowledge in the new textbook of high school. Therefore, the author attempts to prove the butterfly theorem by using the vector as follows Proof method, hoping to arouse the reader’s interest.The butterfly theorem shown in Figure, M is the midpoint of the ⊙O chord EF, AC, BD is two points over the M string, connecting AB, CD, respectively, to pay E