In geometry, an enneadecagon is a polygon with 19 sides and angles. It is also known as an enneakaidecagon or a nonadecagon.
The radius of the circumcircle of the regular enneadecagon with side length t is
- (angle in degrees)
The area of a regular enneadecagon, where t is the edge length, is
A regular enneadecagon cannot be constructed using a compass and straightedge.
The regular enneadecagon is the Petrie polygon for one higher dimensional polytope, projected in a skew orthogonal projection: