Section 3-3 Parallel Lines and Transversals

Properties of Parallel Lines

Corresponding angles postulate If two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent.

Example: 1 2

Alternate interior angles Theorem If two parallel lines are cut by a transversal, then the pairs of alternate interior angle are congruent.

Example: 3 4

consecutive interior angles Theorem If two parallel lines are cut by a transversal, then the pairs of consecutive interior angle are supplementary.

Example: 5 6

Alternate Exterior angles Theorem If two parallel lines are cut by a transversal, then the pairs of alternate exterior angle are congruent.

Example: 7 8

Perpendicular transversal Theorem If a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other.

Example: a b l therefore