---
tag: 0JZ27DMJ5D
kind: concept
name: Dihedral group
msc: [20B25]
sources:
  - url: https://en.wikipedia.org/wiki/Dihedral_group
    locator: lead section
same_as:
  wikidata: Q558339
  wikipedia: Dihedral group
---

## Summary

The dihedral group $D_n$ is the group of the symmetries of a regular polygon with $n$ sides, for $n \geq 3$.
It has $n$ rotations and $n$ reflections, so it has order $2n$.