A pentadecagon has a central angle of 24°. To do this, we need to construct a 60° angle and a 36° angle, and
subtract the two.
- Draw circle O.
- Draw OA and OB,so that they are perpendicular to each other, and A and B are on circle
- Find C, the midpoint of OB.
- Draw a circle at C (dotted) that crosses point A. Circle C crosses OB at point
- Draw a circle at A (purple), crossing point D. This circle crosses circle O at E.
- Draw a circle at E (blue), crossing point A. This circle crosses circle A (purple) at
- Draw a line through points O and F. OF intersects circle O at G.
- Draw another circle at A (cyan), this time crossing O. This new circle crosses circle O
at point H.
- Points G and H are two points of the pentadecagon. Use them to find the rest!