已知：如图,EF是梯形ABCD的中位线,AF平分角DAB求证：AD=2EF
没有图啊
人气：390 ℃ 时间：2019-08-21 09:29:50
解答
图形应该是DC//AB,EF是中位线,AF平分角DAB
证明：因为EF是中位线
所以EF//AB,且DE=EA
所以角EFA=角FAB
又因为AF平分角DAB
所以角EAF=角FAB
即有：角EAF=角EFA
则有：EA=EF
又因为EA=1/2AD
则有EF=1/2AD
所以AD=2EF
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