Exterior Angle

The Exterior Angle is the angle between any side of a shape and a line extended from the next side.

interior exterior angles

Another example:

interior exterior angles

When we add up the Interior Angle and Exterior Angle we get a Straight Angle (180°), so they are "Supplementary Angles".

 

Exterior Angles of Polygons Interior Angles Interior Angles of Polygons Supplementary Angles Angles On a Straight Line Straight Angle Degrees (Angle) Geometry Index