Answer:
ASA Congruence theorem
Explanation:
ASA Congruence theorem stats that if two angles and the side that joins the two angles are equal in two triangles, then the triangles are congruent.
In triangles, ΔABC and ΔDBC, it is clear that
BC = BC (common)
∠B = ∠B (common)
∠C = ∠C (common)
Hence, ΔABC ≅ ΔDBC by ASA congruence theorem.