Step-by-step explanation:
ok, let's try this again. we need to explain congruence then in its details as an implicit part of the proof, as everything boils down to that.
due to AE = FC we also know that ED = BF.
because as ABCD is a parallelogram, it means AD = BC (and AB = DC).
and AD || BC, AB || DC.
as AD = AE + ED and BC = BF + FC, it means that
AE + ED = BF + FC
with AE = FC we can then simplify to
ED = BF.
as AD || BC, so is also ED || BF.
since the distance from E to D is the same as for B to F, it means that EB and DF must be equidistant to each other, and that means they are parallel.
and because ED || BF, that also means that both line segments are equidistant from each other, and that means that the connections between their end points (EB and DF) must have the same lengths.
therefore, the shape is a quadrilateral with 2 pairs of parallel and equally long line segments. and that is the definition of a parallelogram.
so, BEDF is a parallelogram.
