Please help me on proving triangle congruence!!!! Please!

Question

Given: <ADB is a right angle

prove: <ADB = <CDB

Answer 1

Assuming A, D, and C lie on the same line then the proof would go like this:

<ADB is right given

m<ADB = 90° defn. of right angle

<ADB and <CDB are a linear pair defn. of linear pair

m<ADB + m<CDB = 180° angles in a linear pair are suppplementary

90° + m<CDB = 180° substitution

m<CDB = 90° subtraction

<ADB congruent to <CDB defn of angle congruence