Dihedral group

The dihedral group $𝐷 2 𝑛$ is the point symmetry group of an $𝑛$ -gon, consisting of $𝑛$ rotations and $𝑛$ reflections. group Alternatively, it may be constructed as the semidirect product $ℤ 𝑛 ⋊ ℤ 2$ , where $ℤ 𝑛$ represents the rotation group and $ℤ 2$ acts on $ℤ 𝑛$ by inversion.