Words to Know an angle formed by a of a figure and an extension of an exterior angle side polygon in a plane, a closed figure formed from three or more line segments such that each segment exactly two other segments, one at each endpoint, and no segments with a common endpointare regular a polygon that is both polygon and equilateral Angle Measures in Triangles What is the measure of C? 180 54-85 = 54 A B 85