1. Warm Up: 1.Using lined paper and a ruler trace over a set of parallel lines. Then, draw a line intersecting these lines as shown below. 2.Using a protractor, measure each angle. What did you discover? 1 2 3 4 5 6 7 8 a b

2. Vocabulary Review Parallel Lines – two lines that are coplanar and do not intersect Skew lines – lines that do not intersect and are not coplanar Parallel Planes –two planes that do not intersect l m

3. Alternate interior angles: ∠ 3 and ∠ 6, ∠ 4 and ∠ 5 Alternate exterior angles: ∠ 1 and ∠ 8, ∠ 2 and ∠ 7 Consecutive interior angles: ∠ 4 and ∠ 6, ∠ 3 and ∠ 5 Corresponding angles: ∠ 2 and ∠ 6, ∠ 4 and ∠ 8, ∠ 1 and ∠ 5, ∠ 3 and ∠ 7 1 2 3 4 5 6 7 8 a b transversal

4. // and  Postulates Parallel Postulate If there is a line and a point not on the line, then there is exactly one line through the point parallel to the given line. Perpendicular Postulate If there is a line and a point not on the line, then there is exactly one line through the point perpendicular to the given line.

5. Now you try…