what is the angle of an octagon corner
Octagon 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).
Hexagon The common length of the sides equals the radius of the circumscribed circle, which equals    2 3    {\displaystyle {\tfrac {2}{\sqrt {3}}}}  times the apothem (radius of the inscribed circle). All internal angles are 120 degrees. A regular hexagon has 6 rotational symmetries (rotational symmetry of order six) and 6 reflection symmetries (six lines of symmetry), making up the dihedral group D6. The longest diagonals of a regular hexagon, connecting diametrically opposite vertices, are twice the length of one side. From this it can be seen that a triangle with a vertex at the center of the regular hexagon and sharing one side with the hexagon is equilateral, and that the regular hexagon can be partitioned into six equilateral triangles.