解:如图,在AB上截取AF=AD,∴AE平分∠BAD,∴∠DAE=∠FAE,∵AF=AD,AE=AE,∴△DAE≌△FAE,∴∠D=∠AFE,∠DEA=∠FEA,∵AD∥BC,∴∠DAB+∠CBA=180°,∵AE⊥BE,∴∠BAE+∠ABE=90°,∴∠DAE+∠CBE=90°,∴∠ABE=∠CBE,同理,∠FEB=∠CEB,∵BE=BE,∴△BEF≌△BEC,∴BF=BC,∴AB=AF+FB=AD+BC.
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