(1)∵∠BAF+∠BAE=90°,∠DAE+∠BAE=90°,
∴∠BAF=∠DAE,∵AB=AD,∠ADE=∠ABF,
∴△ABF≌△ADE(ASA),∴AE=AF.(5分)
(2)CE=MF.(7分)∵四边形ABCD是正方形,
∴∠AMF=∠ACB=45°,AM=AC,∵△ABF≌△ADE,
∴∠FAB+∠ABF=∠DAE+∠AED,即∠AFB=∠AEC,∴∠MAF=∠EAC,∴△AMF≌△ACE,∴CE=MF.
(3)①如图所示,把△ABE切下,拼到△ADF的位置,∵AB=AD,∠BAE+∠DAE=∠DAF+∠DAE,∴∠BAE=∠DAF,∵∠AEB=∠AFD=90°,∴∠ABE=∠ADF,∴△ABE≌△ADF,∵AE=AD=CE,∠AEC=∠ECF=∠AFC=90°,∴四边形AECF是正方形.
②如图4所示,向左转|向右转
