1. Parallel Lines and Transversals
Sec 12 1-A
pg. 679

2. Definitions
Parallel Lines – lines that do not intersect. l h

3. Definitions a is the r s a
Transversal – a line that intersects two or more lines in a plane at different points a
a is the
transversal to r and s r s

4. Transversals and Angles
Exterior Angles
Interior Angles
1, 2, 7, 8
3, 4, 5, 6 a 1 2 r 4 3 5 6 8 7 s

5. Transversals and Angles
Alternate Exterior Angles
Alternate Exterior Angles are Congruent with parallel lines.
1 and 7,
2 and 8. a 1 2 r 8 7 s

6. Transversals and Angles
Alternate Interior Angles
Corresponding Angles
These angles are congruent with parallel lines.
3 and 5,
4 and 6.
1 and 5,
2 and 6
 3 and 7,
4 and 8. a 1 2 4 r 3 5 6 8 7 s

7. Identify the angles for transversal a a b c Corresponding Angles
1 and 3, 7 and 5
11 and 10, 2 and 9 a
Exterior Angles
Interior Angles
1, 7, 9, 10 1
2, 3, 5, 11 7
Alternate Interior Angles 11 2
5 and 11, 2 and 3 b
Alternate Exterior Angles 3 5
1 and 9, 7 and 10 9 10
Consecutive Interior Angles c
3 and 11, 2 and 5