Co-interior AnglesCo-interior angles are two angles on the same side of the transversal. They are the inside or interior angles and their sums add to 180. Use the two animations below to explore and test this angle relationship. Additionally, in the first animation, drag around the point "A" to manipulate the drawing. Co-interior angles sit on the inside of parallel lines. They appear after a straight line crosses two parallel lines. Each angle pairs with another angle. These pairs form a special total. Each pair sums to 180 degrees. People often call them interior angles on the same side. The angles that lie inside a shape, generally, a polygon, are said to be interior angles, or the angles that lie in the area enclosed between two parallel lines that are intersected by a transversal are also called interior angles. Learn more about interior angles in this article. Free co-interior angles GCSE maths revision guide including step by step examples, and free co-interior angles worksheet and exam questions.
