设B、D到AB的垂线段长为h．∵AD=BC,AD‖BC,且DE⊥AC,BF⊥AC,∴△AED≌△BCF．同理△AEB≌△DCF．∴AE=CF,S△AED=S△BCF=S△AEB=S△DCF．又在△ACB中,tan∠ACB= AB/BC= 50根2/50=根 2,且∠DAC=∠ACB,∴在△AED中,tan...