


Description 



Exterior Angle: An exterior angle of a polygon is formed when you extend a side of a polygon. Also, when a third line (a transversal) crosses two other lines, the angles formed outside the other two lines are called exterior angles. (see alternate exterior angles) 
An angle is an exterior angle of a polygon if and only if it
forms a linear pair with one of the angles of the polygon. Notice that by extending each side of the triangle, there are 6 (not 9) exterior angles.
Angles 1, 2, 3, and 4 are all exterior angles.


