Geo Theorem 2.5 Congruent Complements

Exploration for the complement Theorem[br][br]Move Point B or F to match the angle measures. How does matching the angle measures confirm the validity of the Complement Theorem - Complements of congruent angles are congruent.
What are complementary angles?[br][br]How do we know the pairs of adjacent angles are complementary?[br][br]Under what condition can it be said that <ADB is congruent to <FDG?

Information: Geo Theorem 2.5 Congruent Complements