1. Use Parallel Lines and Transversals

2. Let’s Investigate! 1 2 3 4 5 6 7 8

3. Postulate 15 Corresponding Angles If two parallel lines
are cut by a transversal
then the pairs of
corresponding angles
are congruent. 1 2 3 4 5 6 7 8

4. Theorem 3.1 Alternate Interior Angles Theorem
If two parallel lines are cut by a
transversal, then the
pairs of alternate
interior angles are
congruent. 1 2 3 4 5 6 7 8

5. Theorem 3.2 Alternate Exterior Angles Theorem
If two parallel lines are cut by a transversal,
then the pairs of alternate exterior angles
are congruent. 1 2 3 4 5 6 7 8

6. Theorem 3.3 Consecutive Interior Angles Theorem
If two parallel lines are cut by a transversal, then
the pairs of consecutive interior angles
are supplementary. 1 2 3 4 5 6 7 8

7. Find angles 1 and 2 for each problem.1. 2.
120, 120
120, 60 3. 4.
140, 140
135, 45

8. Let’s Try!
Find the value of x.
115o 4
(x + 5)o

9. Let’s Try! If , find the measures of angles 4, 5 and 8. If and
what is the value
of x? 1 2 3 4 5 6 7 8

10. Find x. 1. 2. 40 40 3. 4.
110 33

11. Word Problem
135 45
140
130

12. Homework p.