It is known that ab ‖ De, BC ‖ EF, D, C are on AF, and ad = CF

It is known that ab ‖ De, BC ‖ EF, D, C are on AF, and ad = CF

It is proved that ∵ ab ∥ De, BC ∥ EF ∥ a = ∥ EDF, ∥ f = ∥ BCA and ∵ ad = CF ∥ AC = DF ≌ ABC ≌ def. (ASA)