Accreditation is a process in which school standards are evaluated by an accreditation agency. In the United States, this process is not completed by the federal government, but by states or private companies with varying rules and standards. Different groups promote accreditation for homeschoolers.
The circle is the simplest and best known conic section. As a conic section, the circle is the intersection of a plane perpendicular to the cone's axis. The geometric definition of a circle is the locus of all points a constant distance r {\displaystyle r} from a point ( h , k ) {\displaystyle (h,k)} and forming the circumference (C).
The circle is a highly symmetric shape: every line through the centre forms a line of reflection symmetry and it has rotational symmetry around the centre for every angle. Its symmetry group is the orthogonal group O(2,R). The group of rotations alone is the circle group T. All circles are similar. A circle's circumference and radius are proportional.