Answer:
∠ABC ≅ ∠ABD + ∠DBC
Explanation:
The angle addition postulate is applied a larger angle is divided into two smaller angles that share the same vertices, the measure of the larger angle is the sum of the two smaller angles. That is the resulting angle formed by two angles which are side by side is the sum of the two angles. In triangle ABC, if ∠ABC is divided by line BD then ∠ABC is divided into ∠ABD and ∠DBC. Therefore:
∠ABC ≅ ∠ABD + ∠DBC