A regular tridecagon, also called the regular triskaidecagon, is a regular polygon with 13 sides.
Regular Tridecagon
See also
Tridecagon, Regular PolygonExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Regular Tridecagon." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RegularTridecagon.html