I need to write a two-column proof given angle 1 and angle 2 are supplementary and angle 1 and angle 3 are congruent . I have to prove angle 2 and angle 3 are supplementary .

Answer 1

∠1 and ∠2 are supplementary Given

∠1 ≅ ∠3 Given

m(∠1) + m(∠2) = 180° The sum of the measures of supplementary angles is 180°

m(∠3) + m(∠2) = 180° Substitution

∠2 and ∠3 are supplementary If the sum of the measures of two angles is 180°, then they are

supplementary.