Question

What additional information do you need to prove ∆ABC ≅ ∆DEF by the SAS Postulate?

Answer 1

Answer: BC = EF (third choice)

The acronym SAS stands for "side angle side". Specifically it refers to using two pairs of sides, and one pair of angles between the sides, to prove the triangles congruent.

We are given that AC = FD as one pair of congruent sides (shown by the similar tickmarks). Also, we are given the angles C and F are congruent as well. We need another pair of sides to be congruent. We can't use AB and DE because those sides are not adjacent to the congruent angles mentioned. So the only thing possible is BC = EF

Check out the attached image below.