| 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 "sept-" (an elision of septua-, a Latin-derived numerical prefix, rather than hepta-, a Greek-derived numerical prefix; both are cognate) together with the Greek suffix "-agon" meaning angle.