Explanation: Proving that two triangles are congruent by SSS means that we want to prove that each side in the first triangle is equal to its corresponding side in the second one. The distance formula is the one to get you the side lengths.
Assume that we want to prove that triangle ABC is congruent to triangle DEF by SSS. We will use the distance formula to get the lengths of: AB BC AC DE EF DF Then, we will check the side length that we calculated, if we find that: AB = DE BC = EF AC = DF Then, the two triangles are congruent by SSS
