边形ABCD中ABCDBEDFAE⊥BDCF⊥BD垂足分别为EF1求证△ABE≌△CDF2若AC与BD交于点O求证AOCO
B
A
EO11题
DF
C
4、（8分）如图在△ABC中∠CAB900DEDF是△ABC的中位线连接EFAD
B
求证EFAD
D
F
C
E
A
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