∠ABD=∠EBC=90°-∠ABC
BD=BC,AB=AE
所以△ABD≌△EBC
所以∠BDF=∠BCE
∠CDF=∠BDF-45°
∠FCD=180°-45°-∠BCE=135°-∠BDF
∠EFD=180°-(∠CDF+∠FCD)
=180°-(135°-45°)=90°
所以DF 垂直于EF
∠ABD=∠EBC=90°-∠ABC
BD=BC,AB=AE
所以△ABD≌△EBC
所以∠BDF=∠BCE
∠CDF=∠BDF-45°
∠FCD=180°-45°-∠BCE=135°-∠BDF
∠EFD=180°-(∠CDF+∠FCD)
=180°-(135°-45°)=90°
所以DF 垂直于EF