Using Triangle Congruence Theorems Answers

Which congruence theorem can be used to prove △BDA ≅ △BDC?

Given: ∠GHD and ∠EDH are right; GH ≅ ED

Which congruence theorem can be used to prove △WXZ ≅ △YZX?

Consider the diagram.

Line segments AD and BE intersect at C, and triangles ABC and DEC are formed. They have the following characteristics: ∠ACB and ∠DCE are vertical angles∠B ≅ ∠EBC ≅ EC