
alternate interior angles


Either pair of interior angles lying on opposite sides of the transversal, which are formed when a transversal cuts two lines, such as 3 and 6 or 4 and 5.
When a transversal cuts two parallel lines, 3 = 6 and 4 = 5. In addition, 3 + 5 = 180° and 4 + 6 = 180°.

