∵AE⊥BD CF⊥BD
∴∠AEB=∠CFB ∠A+∠ABE=∠C+∠CBF=90
∵AB⊥BC
∴∠ABE+∠CBF=90
∴∠A=∠CBF
∵AB=BC
∴△AEB全等于△BFC
∴AE=BF EB=FC
∴FC=EB=EF+BF=EF+AE