请教一道数学题，谢谢！

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• 10 -deAnng- ♂ (0 bytes) () 09/01/2012 postreply 16:34:54

• 10 -网恋无罪- ♂ (148 bytes) () 09/01/2012 postreply 19:06:54

• Thank you very much! why HE＊EG＝FE＊ED? -abct- ♀ (0 bytes) () 09/02/2012 postreply 16:16:33

• 两对相似三角形 -文学村民- ♂ (2188 bytes) () 09/02/2012 postreply 08:46:02

• Thank you very much! but why △EFG∽△EHD? -abct- ♀ (0 bytes) () 09/02/2012 postreply 16:14:43

• 看看intersecting chord theorem. -壮士- ♂ (0 bytes) () 09/02/2012 postreply 17:34:45

• Thank you very much, studying~ -abct- ♀ (0 bytes) () 09/04/2012 postreply 08:13:43

• 回复：Thank you very much! but why △EFG∽△EHD? -文学村民- ♂ (8817 bytes) () 09/02/2012 postreply 20:03:00

• Thank you very much! got it! -abct- ♀ (0 bytes) () 09/04/2012 postreply 08:14:26