Sum of the exterior angles of polygons. When we dont know the Apothem we can use the same formula but re-worked for Radius or for Side. Pin On Geometry The sum of interior angles div number of sides. . In case if the given polygon is an irregular polygon then we add the lengths of all the given sides and subtract it from the perimeter to get the missing side. Since the polygon has 3 exterior angles it. Therefore all its exterior angles measure the same as well that is 120 degrees. Here m n o p q 360 Angles in Regular Polygon. Exterior angles 360⁰n. An exterior angle of a polygon is made by extending only one of its sides in the outward direction. In this case we have the measure of an internal angleTherefore we can find the measure of its corresponding exterior angle by subtracting the angle from 180. Sum of the exterior angles of polygons 360 The sum will always be equal to 360 degrees irrespective of the