Reflection symmetry (2D)

A1×I, also known as dyadic symmetry, is a 2D spherical Coxeter group. It is the symmetry group of the isosceles triangle and corresponds to mirror symmetry. It has only one reflectional elemnt. Every polygonal symmetry has this as a subsymmetry, and it is the symmetry of any bilaterally-symmetric polygon.

Subgroups

 * I×I