Heptagon

Regular heptagon
A regular heptagon
Type	Regular polygon
Edges and vertices	7
Schläfli symbol	{7}
Coxeter–Dynkin diagrams
Symmetry group	Dihedral (D7), order 2×7
Internal angle (degrees)	≈128.571°
Properties	Convex, cyclic, equilateral, isogonal, isotoxal
Dual polygon	Self

In geometry, a heptagon or septagon is a seven-sided polygon or 7-gon.

The heptagon is sometimes referred to as the septagon, using septa- (an elision of septua-), a Latin-derived numerical prefix, rather than hepta-, a Greek-derived numerical prefix (both are cognate), together with the suffix -gon for Greek: γωνἰα, romanized: gonía, meaning angle.