To find the missing reason in Huy's proof, we need to look closely at the statements provided.
- m∠A + m∠C = 180° (Linear pairs are supplementary)
- m∠A = m∠E
- m∠E + m∠C = 180° (Substitution)
- ∠E and ∠C are supplementary (Definition of supplementary angles)
The missing reason needs to justify why m∠E + m∠C = 180° based on the previous steps. Given that m∠A = m∠E, we substitute m∠E for m∠A in the first statement.
Thus, the reason for step 3 should be the Transitive Property of Equality since it is stating that if m∠A = m∠E and we already know m∠A + m∠C = 180°, we can replace m∠A with m∠E.
Correct answer:
Transitive Property of Equality