Vertical angles are angles that are opposite each other when two lines intersect. Corresponding angles are angles that are in the same relative position to the point of intersection but on opposite sides of the intersecting lines. Alternate exterior angles are nonadjacent angles outside of the intersecting lines formed by a transversal crossing two parallel lines. Alternate interior angles are nonadjacent angles inside of the intersecting lines formed by a transversal crossing two parallel lines.