过E做EG⊥AF于G，连接EF∵ABCD是正方形∴∠D=∠C=90° AD=DC∵∠DAE=∠FAE，ED⊥AD，EG⊥AF∴DE=EG AD=AG∵E是DC的中点∴DE=EC=EG∵EF=EF∴Rt△EFG≌Rt△ECF∴GF=CF∴AF=AG+GF=AD+CF 额 so easy
