Use Parallel Lines and Transversals

Let’s Investigate! 1 2 3 4 5 6 7 8

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

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

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

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

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

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

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

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

Word Problem 135 45 140 130

Homework p.