延长EB′与AD交于点F；∵∠AB′E=∠B=90°，MN是对折折痕，∴EB′=FB′，在△AEB′≌△AFB′，AB′＝AB′∠AB′E＝∠AB′FEB′＝FB′∴△AEB′≌△AFB′，∴AE=AF，∴∠B′AE=∠B′AD（等腰三角形三线合一），故根据...