
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
O.
 Find C, the midpoint of OB.
 Draw a circle at C (dotted) that crosses point A. Circle C crosses OB at point
D.
 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
F.
 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!
