Circle

Center – The equidistant of a given circle

Central angle – An angle whose vertex is the center of a circle

Chord – A segment whose end points are on the circle

Circle - A set of all points in a plane that are equidistant from a given point

Circumscribed – If a polygon is inscribed the circle is circumscribed

Common Tangent – A line or segment that is tangent to two coplanar circles

Concentric – two circles sharing the same center point

Congruent – If two circles have the same radius, they are congruent

Congruent arc – Two arcs of same circle or congruent circle of the same size

Diameter – The distance from across the circle through the center point

Exterior of a circle – The points that are outside the circle

Inscribed – If all of the vertices of a polygon lie on a circle

Inscribed Angle – An angle whose vertex is on a circle and whose side contains chords of the circle

Intercepted Arc – The arc that lies in the interior of an inscribed angle and has an end point on the angle.

Interior of a circle – The points that are inside the circle