Given: 1 || m; transversal t cuts I and m Prove: 21 and 27 are supplementary
Statement
Reason
1.1 || m; transversal t cuts I and m
1. Given
2. Z1 Z3, Z527
2. Vertical Angles Theorem
3. mZ1 = m 3, mZ5 = m27
3. Definition of congruent angles
4. 23 and 25 are supplementary
4.
5. mZ3+ m25 = 180°
5. Definition of supplementary angles
6. mZ1 + m27 = 180°
6. Substitution Property
7. Z1 and 27 are supplementary
7. Definition of supplementary angles
What is the missing reason in the proof above? Explain your reasoning.