If you cut a regular octagon into triangles, it would be 6 triangles. the measurement of all the angles in a triangle added up are 180 degress multiply 6x180=1080 the measurement of all the angles in a octagon added up are 1080 degress there are 8 angles in a octagon. divide 1080 by 8=135 135 degress in each angle in a regular octagon
Whether it is a regular or irregular octagon does not matter. An octagon is, by definition, a 2-dimensional figure with eight sides, and therefore with eight angles. A regular octagon will have eight equal angles and an irregular octagon will have eight angles some of which are not equal to the others.