In geometry, a transversal is a line that intersects two or more other (often parallel ) lines.

What happens when parallel lines are intersected by a transversal?

If two parallel lines are cut by a transversal, then, Alternate Interior Angles are congruent. If two parallel lines are cut by a transversal, then, Alternate Exterior Angles are congruent. If two parallel lines are cut by a transversal, then corresponding angles are congruent.

Are parallel lines cut by transversal supplementary?

When the lines are parallel, the interior angles on the same side of the transversal are supplementary. If two parallel lines are cut by a transversal, the interior angles on the same side of the transversal are supplementary.