The correct statement to place at the end of the proof is:
"Finally, corresponding parts of congruent triangles are congruent by the CPCTC Theorem, so ∠A≅∠C."
This is because you have proven that triangles ΔABD and ΔCBD are congruent, and by the Corresponding Parts of Congruent Triangles are Congruent (CPCTC) theorem, the corresponding angles ∠A and ∠C must also be congruent.