1. 3.3: Proving Lines parallel

2. 1. Draw AB and AC, where A, B, and C are noncollinear.
Review
1. Draw AB and AC, where A, B, and C are noncollinear.
Draw opposite rays DE and DF.
State the converse of each statement.
3. If a = b, then a + c = b + c.

3. 1. Draw AB and AC, where A, B, and C are noncollinear.
Review
1. Draw AB and AC, where A, B, and C are noncollinear.
Draw opposite rays DE and DF.
State the converse of each statement.
3. If a = b, then a + c = b + c.

6. In other words,
If corresponding angles are __________ then the lines are parallel.
If alternate interior angles are __________, then the lines are parallel.
If alternate exterior angles are ___________, then the lines are parallel.
If same-side interior angles are ____________, then the lines are parallel.
**Vertical angles, adjacent angles, and linear pairs do not prove lines being parallel or not.**