延长FD交于CB的平行线于G,即AG‖FB.∴∠EAG=90°
∵AG‖FB,∴∠B=∠DAG,AD=DB,∠CDB=∠GDA∴△AGD≌△BFD
∴AG=FB,DG=DF
DG=DF,ED=ED,∠EDF=∠EDG=90°,∴△EDG≌△EDF
∴EG=EF
在Rt△EAG中有AE^2+AG^2=EG^2,
EG=EF,AG=FB
∴EF^2=AE^2+FB^2
延长FD交于CB的平行线于G,即AG‖FB.∴∠EAG=90°
∵AG‖FB,∴∠B=∠DAG,AD=DB,∠CDB=∠GDA∴△AGD≌△BFD
∴AG=FB,DG=DF
DG=DF,ED=ED,∠EDF=∠EDG=90°,∴△EDG≌△EDF
∴EG=EF
在Rt△EAG中有AE^2+AG^2=EG^2,
EG=EF,AG=FB
∴EF^2=AE^2+FB^2