1. Chapter 3 Perpendicular & Parallel Lines Sec. 3.1 Lines and Angles GOALS: To identify relationships between lines and angles formed by transversals

2. Vocabulary Perpendicular lines – two lines that intersect to form a right angle. k h k h d P Parallel lines – two lines that are coplanar and do not intersect.

3. Vocabulary Cont. Skew lines – lines that do not intersect and are not coplanar. lm Parallel Postulate There is exactly one line through P parallel to l. P l

4. Vocabulary Cont. Perpendicular Postulate There is exactly one line through P perpendicular to l. P l

5. 7 Transversal Transversal - a line that intersects two or more coplanar lines. Eight angles are formed. 8 43 65 2 1 t

6. 7 Special Angles Names ( for two lines cut by a transversal) 8 43 65 2 1 Corresponding angles - those in the same position on each line in relation to the transversal.

7. Special Angles Names Cont. ( for two lines cut by a transversal) 43 65 Alternate interior angles - they alternate (cross over ) the transversal and are inside the two lines

8. 7 Special Angles Names Cont. ( for two lines cut by a transversal) 8 2 1 Alternate exterior angles - on opposite sides of the transversal and are outside the two lines

9. 5 Special Angles Names Cont. ( for two lines cut by a transversal) 6 4 3 Consecutive interior angles - on the same side of the transversal and are inside the two lines)

10. Example What kind of angles are angles 4 and 5? k h t

11. Example What kind of angles are angles 11 and 12? k h t

12. Example What kind of angles are angles 11 and 12? k h t

13. 7 Example List all pairs of: Alternate Exterior Angles Alternate Interior Angles Corresponding Angles Consecutive Interior Angles (same-side interior) Vertical Angles Linear Pairs 8 43 65 21