Question

What is the reason for the third step in this proof?

Given: a || b, and both lines are cut by transversal t.

Prove: 2 7
Proof:
Statement Reason
1. a || b given
2. 2 3 Vertical Angles Theorem
3. 3 6
4. 2 6 Transitive Property of Congruence
5. 6 7 Vertical Angles Theorem
6. 2 7 Transitive Property of Congruence

Transitive Property of Equality

Alternate Interior Angles Theorem

Corresponding Angles Theorem

Same-Side Interior Angles Theorem

Vertical Angles Theorem

Answer 1

@gelow

Answer 2

@lakeykey