Answer:
CB // ED and both of BD and CE are transversals
The point E will be the image of point C by rotation 180° around point F
And The point D will be the image of point B by rotation 180° around point F
Rotation is a kind of transformation
So, ΔEDF will be the image of ΔCBF
So, ΔCBF ≅ ΔEDF
Another way:
So, ∠B = ∠D Alternate angles are congruent
and ∠C = ∠E Alternate angles are congruent
So, ΔCBF and ΔEDF have the following
1) ∠C = ∠E ⇒⇒⇒ Alternate angles are congruent (proved)
2) CB ≅ ED ⇒⇒⇒ Given
2) ∠B = ∠D ⇒⇒⇒ Alternate angles are congruent (proved)
From 1, 2 and 3
So, ΔCBF ≅ ΔEDF By SAS postulate