Heptagon and Heptagrams / Septegrams. Level: High School, SAT Prep, College.

A heptagon is a polygon with seven sides and seven angles.

A regular heptagon is a polygon which is equiangular (all angles are congruent) and equilateral (all sides have the same length).

A heptagram or septegram is a seven-pointed star drawn with seven straight strokes.

There are two regular heptagrams, labeled by Schlafli symbols as {7/2} and {7/3}, with the second number representing the vertex interval step from a regular heptagram, {7/1}.

The Schlafli symbol is a notation of the form {p,q,r,...} that defines regular polytopes and tessellations.