在菱形ABCD中,AC、BD交于点O∴OA=OC,∠BAO=∠DAO∵OE⊥AB,OH⊥AD∴OE=OH∵AB∥CD,OE⊥AB并反向延长OE交CD于点G∴∠AEO=∠CGO=90°∠BAO=∠DCO∵OA=OC∴⊿AOE≌⊿COG(AAS)∴OE=OG同理OH=OF∴四边形EFGH是平行四边形∵...