Angle 1 and angle 2 form a linear pair; angle 1 and 3 are congruent . Prove angle 2 and angle 3 are supplementary

Answer 1

The sketch of the proof is as follows.

Angles 1 and 2 are on a line, thus their sum is 180^o.

Angles 1 and 3 are congruent, thus they have the same value

Angles 1 and 2 have the same sum as angles 2 and 3.

A pair of angle whose sum is 180 degrees is ____________.

Fill in the details and you have your proof.