| parallel lines | Two lines that lie in the same plane that do not intersect |
| parallel planes | Planes that do not intersect |
| skew lines | Two nonparallel lines that do not intersect |
| transversal | In a plane, a line that intersects two or more lines, each at a different point |
| slope | The ratio of the rise, or vertical change, to the run, or horizontal change |
| linear equation | An equation whose graph is a straight line |
| y-intercept | The y value of the point where a line crosses the y-axis |
| slope-intercept form | The form of a linear equation written as y = mx + b |
| Corresponding Angles | If two parallel lines are cut by a transversal, then each pair of corresponding angles are ___ |
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| Postulate 4-2 | In a plane, if two lines are cut by a transveral so that a pair of corresponding angles is congruent, then the lines are ___ |
| Postulate 4-3 | Two nonvertical lines are parallel if and only if they have the same ___ |
| Postulate 4-4 | Two nonvertical lines are ___ if and only if the product of their slope is -1 |
| Alternate Interior Angles | If two parallel lines are cut by a ___, then each pair of alternate interior angles are congruent |
| Consecutive Interior Angles | If two parallel lines are cut by a transversal, then each pair of consecutive interior angles are ___ |
| Perpendicular Transversal | If a transversal is perpendicular to one of two parallel lines, it is ___ to the other |
| Theorem 4-5 | In a plane, if two ___ are cut by a transversal so that a pair of alternate interior angles is congruent, then the two lines are parallel |
| Theorem 4-6 | In a ___, if two lines are cut by a transversal so that a pair or alternate exterior angles is congruent, then the two lines are parallel |
| Theorem 4-7 | In a plane, if two lines are cut by a transveral so that a pair of consecutive interior angles is supplementary, then the two lines are ___ |
| Theorem 4-8 | In a plane, if two lines are perpendicular to the same ___, then the two lines are parallel |