Question

A polygon having its vertices at a circle called _____

Answer 1

$\red { \fbox \mathtt \blue{concyclic \: polygon}}$

The center of this circle is called the circumcenter and its radius is called the circumradius. Not every polygon has a circumscribed circle. A polygon that does have one is called a cyclic polygon, or sometimes a concyclic polygon because its vertices are concyclic.