延长CB至点G,使BG=DF∵AB=AD,BG=DF,∠GBA=∠FDA=90∴△ABG和△ADF全等,∠GAB=∠FAD,AG=AF∵∠EAF=45,∠BAD=90∴∠GAE=90-∠EAF=45∵∠GAE=∠EAF,AG=AF,AE=AE∴△GAE和△FAE全等,EG=EF设正方形边长为a,则BC+BG=a+DF=a...