连接AC,BD,EG
由E,F为AB,BC中点
则EF=AC/2
同理GH=AC/2,FG=BD/2,EH=BD/2
则EF=GH,FG=EH
又EG=EG,△EGF≌△GEH
则∠GEF=∠EGH
EF‖GH
四边形EFGH是平行四边形
己知空间ABCD四边形中,E,F,G,H分别是AB,BC,CD,DA的中点;求证:四边形EFGH是平行四边形.
己知空间ABCD四边形中,E,F,G,H分别是AB,BC,CD,DA的中点;求证:四边形EFGH是平行四边形.
数学人气：474 ℃时间：2019-10-19 14:59:40
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