Question: are all sides of an octagon the same size

Answer: Yes, A regular octagon is a closed figure with sides of the same length and internal angles of the same size. It has eight lines of reflective symmetry and rotational symmetry of order 8. A regular octagon is represented by the Schläfli symbol (8). The internal angle at each vertex of a regular octagon is 135° ( 3 π 4 (\displaystyle \scriptstyle (\frac (3\pi )(4))) radians). The central angle is 45° ( π 4 (\displaystyle \scriptstyle (\frac (\pi )(4))) radians).