We have been given an diagram and we are asked to find the congruence theorem that can be used to prove △LON ≅ △LMN.
We can see from our diagram that side LO of △LON equals to side LM of △LMN. We can also see that side ON △LON of equals to side MN of △LMN. Side LN equals to itself.
We can see that three sides of triangle LON are congruent to three sides of triangle LMN. Therefore, by SSS (Side-Side-Side) congruence △LON ≅ △LMN.
