The sum of the interior angles of a 14-gon = (14-2)*180 = 2,160 degrees. There are 14 vertexes (vertices) for a 14-gon. It is 'regular' so all these angles are equal. By dividing 2160 (sum of all angles) by 14 (total amount of angles) we can see how much each angle is worth. So the interior angle of each is 154.285 degrees.
