is angle abd congruent to angle cbd
We will use the SAS (SIDE-ANGLE-SIDE) to prove that the two triangles are congruent. This states that if two sides and the included angle in one triangle are congruent to two sides and the included angle of another triangle, then the two triangles are congruent. First line. First column: AB is congruent to CB Second column: Given. Second line. First column: angle ABD is congruent to angle CBD Second column: Given. At this point we have the SIDE-ANGLE portion of SAS. We just need the other side. We can see from the given angles that they both share a side...BD.