第1个回答 2011-06-28
解:因为 AB =AC,
所以 ∠ABC =∠ACB.
又因为 BF, CE分别是 ∠ABC 和∠ACB的平分线,
所以 ∠ABF =∠CBF =(1/2) ∠ABC,
∠ACE =∠BCE =(1/2) ∠ACB.
所以 ∠ABF =∠CBF =∠ACE =∠BCE.
由 ∠EBC =∠FCB,
BC =BC,
∠ECB =∠FBC,
得 ΔEBC≌ΔFCB (ASA).
所以 BE =CF,
且 ∠BEC =∠CFB.
由 ∠BEO =∠CFO,
BE =CF,
∠EBO =∠FCO,
得 ΔBEO≌ΔCFO (ASA).
所以 OE =OF.