∫AB∨FC
∴∠B=∠FCE (two straight lines are parallel and have the same included angle)
∫AD∨FE
∴∠ ADB =∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠∠
BC = DE
∴BC+CD=DE+CD
That is BD=CE.
In Abd and FCE
Big ∠B=∠FCE
Closed BD=CE
No ∠ADB=∠E
∴△Abd?△FCE
∴AD=FE (two corresponding sides of congruent triangles are equal)
Well, because braces are not easy to type, I have to write them.