Right I have been given the following problem and cannot resolve it. I have had an attempt but without much success. Could anyone help me with this exercise, please? Hints or a little more welcome :-) A cyclic hexagon is a hexagon whose vertices all lie on the circumference of a circle. The vertices of a cyclic hexagon are labelled in order A to F. Prove that the sum of the interior angles at A, C and E is equal to the sum of the interior angles at B, D and F. Generalise (concisely) to other cyclic polygons?