| A | B |
|---|
| corresponding angles postulate | (Postulate) If two parallel lines are cut by a transversal, then the pairs of corresponding angles are congruent |
| alternate interior angles theorem | (theorem) If two parallel lines are cut by a transversal, then the pairs of alternate interior angles are congruent |
| consecutive interior angles theorem | (theorem) If two parallel lines are cut by a transversal, then the pairs of consecutive interior angles are supplementary |
| alternate exterior angles theorem | (theorem) If two parallel lines are cut by a transversal, then the pairs of alternate exterior angles are congruent |
| perpendicular transversal theorem | (theorem) If a transversal is perpendicular to one of two parallel lines, then it is perpendicular to the other |
| corresponding angles converse postulate | (postulate) If two lines are cut by a transversal so that corresponding angles are congruent, then the lines are parallel |
| alternate interior angles converse theorem | (theorem) If two lines are cut by a transversal so that alternate interior angles are congruent, then the lines are parallel |
| consecutive interior angles converse theorem | (theorem) If two lines are cut by a transversal so that consecutive interior angles are supplementarythen the lines are parallel |
| alternate exterior angles converse theorem | (theorem) If two lines are cut by a transversal so that alternate exterior angles are congruent, then the lines are parallel |
| slopes of parallel lines postulate | (postulate) In a coordinate plane, two nonvertical lines are parallel if and only if they have the same slope |
| slopes of perpendicular lines postulate | (postulate) In a coordinate plane, two nonvertical lines are perpendicular if and only if the product of their slopes is -1 |
