As shown in the figure, parallelogram ABCD, e, f are two points on AC, de ‖ BF, verification: AE = CF

As shown in the figure, parallelogram ABCD, e, f are two points on AC, de ‖ BF, verification: AE = CF

It is proved that: as shown in the figure, ∵ quadrilateral ABCD is a parallelogram, ∵ ad ∥ BC, ad = BC, ∥ DAE = ∥ BCF. De ∥ BF, ∥ def = ∥ BFE, ∥ AED = ∥ CFB. In △ ade and △ CBF, DAE = ∥ bcfad = CB ∥ ade = ≌ CBF (ASA), ≌ AE = CF