Answer:
The correct options are;
1. Definition of supplementary angles
2. m∠1 + m∠2 = m∠1 + m∠3
3. m∠2 = m∠3
4. Definition of congruent angles
Step-by-step explanation:
The two column proof is presented as follows;
Statement Reason
1. ∠1 and ∠2 are supplementary Given
∠1 and ∠3 are supplementary
2. m∠1 + m∠2 = 180° (1) Definition of supplementary angles
m∠1 + m∠3 = 180°
3. (2) m∠1 + m∠2 = m∠1 + m∠3 Transitive Property
4. (3) m∠2 = m∠3 Subtraction property of equality
5. ∠2 ≅ ∠3 (4) Definition of congruent angles
Given that angles ∠1 and ∠2 are supplementary, we have, ∠1 + ∠2 = 180°
Given that angles ∠1 and ∠3 are also supplementary, we also have, ∠1 + ∠3 = 180°
∴ ∠1 + ∠2 = 180° = ∠1 + ∠3
∠1 + ∠2 = ∠1 + ∠3
∠1 + ∠2 - ∠1 = ∠1 + ∠3 - ∠1
∴ ∠2 = ∠3
∴ ∠2 ≅ ∠3, by definition of congruent angles.