## Geometry: Common Core (15th Edition)

In these two triangles, two consecutive angles on each of the triangles are congruent. The included side is also congruent. Therefore, we can prove that these triangles are congruent using the ASA theorem, which states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then those two triangles are congruent. We can say that $\triangle BCE$ is congruent to $\triangle DCE$. Congruent triangles have congruent sides, so $\overline{BE} ≅ \overline{DE}$.