On simple regular two-dimensional geometric objects with straight edges: polygons, n-gons
Polygon or n-gon means a multiple-sided or multiple-edged figure. Simple regular polygons are convex shapes in which all sides are of equal length and all vertices have the same angle. All sides are straight. Convex means facing outward. Thus, there are no inward-facing edges. This means that all interior angles of convex polygons measure greater than 0 degrees and less than 180 degrees. The interior angles of regular polygons increase as the number of vertices increases, starting at 60 degrees and approaching 180 degrees. Specifying a single side length precisely defines the corresponding polygon, allowing all other values to be calculated from it.
The minimum number of vertices for a regular polygon on a euclidean plane is three. There is no upper limit. The more vertices a regular polygon has, the more it resembles a circle when the scale is the distance from the vertices to the center. The simplest regular polygon is the equilateral triangle. The next and probably most well-known is the square. This page features calculators for regular polygons ranging from the triangle up to the dodecagon with 12 sides, as well as the hexadecagon with 16 sides and a general regular polygon. The latter allows for calculations with any number of vertices. While this makes the formulas somewhat more complex, for the user it simply means entering an additional value, the number of vertices, alongside the side length. Finally, there is a calculator for a polygon ring. This is not one single regular polygon, but two. These share the same number of vertices, with the smaller one removed centrally from the larger one.