Section 3-2: Properties of Parallel Lines

Corresponding Angles

Angles that lie on the same side of the transversal and in corresponding positions

Parallel Lines

Coplanar lines that do not intersect

Theorem 3-3: Alternate Exterior Angles Theorem

If a transversal intersects two parallel lines, then alternate exterior angles are congruent.

Theorem 3-1: Alternate Interior Angles Theorem

If a transversal intersects two parallel lines, then alternate interior angles are congruent.

Theorem 3-2: Corresponding Angles Theorem

If a transversal intersects two parallel lines, then corresponding angles are congruent.

Postulate 3-1: Same-Side Interior Angles Postulate

If a transversal intersects two parallel lines, then same-side interior angles are supplementary.

Same-side Interior Angles

Interior angles that lie on the same side of the transversal

Alternate Exterior Angles

Nonadjacent exterior angles that lie on opposite sides of the transversal

Alternate Interior Angles

Nonadjacent interior angles that lie on opposite sides of the transversal

Skew Lines

Noncoplanar lines that are not parallel and do not intersect

Parallel Planes

Planes that do not intersect

Transversal

A line that intersects two or more coplanar lines at distinct points