| Regular decagon | |
|---|---|
 A regular decagon | |
| Type | Regular polygon |
| Edges and vertices | 10 |
| Schläfli symbol | {10}, t{5} |
| Coxeter–Dynkin diagrams |     |
| Symmetry group | Dihedral (D10), order 2×10 |
| Internal angle (degrees) | 144° |
| Properties | Convex, cyclic, equilateral, isogonal, isotoxal |
| Dual polygon | Self |
In geometry, a decagon (from the Greek δέκα déka and γωνία gonía, "ten angles") is a ten-sided polygon or 10-gon.[1] The total sum of the interior angles of a simple decagon is 1440°.
- ^ Sidebotham, Thomas H. (2003), The A to Z of Mathematics: A Basic Guide, John Wiley & Sons, p. 146, ISBN 9780471461630.