A polygon is inscribed in a circle if all its vertices are points on the circle and all sides are included within the circle. All regular polygons can be inscribed in a circle. The center of an inscribed polygon is also the center of the circumscribed circle.
polygon inscribed in a circle, ellipse, or polygon (or a polyhedron inscribed in a sphere, ellipsoid, or polyhedron) has each vertex on the outer figure; if the outer figure is a polygon or polyhedron, there must be a vertex of the inscribed polygon or polyhedron on each side of the outer figure.
