I have a new page: Properties of Regular Polygons hope you enjoy.
I would appreciate someone checking the calculations etc to make sure I haven't made a silly error, before I "publish" it.
I found one small error/typo:
"The external angle is just 180° - (!)External Angle(!)
The internal angle of this octagon is 135°, so the external angle is 180°-135° = 45°"
Thanks, Ehiness. Ha!