**
Arc
** -
Two endpoints on a circle and all of the
points on the circle between those
two
endpoints.

**
Center
** -
The point from which all points on a
circle are equidistant.

**
Central Angle
** -
An angle whose
vertex is the center of a
circle.

**
Chord
** -
A segment whose endpoints are on a
circle.

**
Circle
** -
A geometric figure composed of points that
are equidistant from a given point.

**
Circle Segment
** -
The region within a circle bounded by a chord of that circle and the
minor arc whose endpoints are the same as those of the chord.

**
Circumscribed Polygon
** -
A polygon whose segments are tangent
to a
circle.

**
Concentric Circles
** -
Circles that share a center.

**
Diameter
** -
A chord that intersects with the center of a circle.

**
Equidistant
** -
The same distance. Objects can be equidistant from one another.

**
Inscribed Polygon
** -
A polygon whose
vertices intersect with a circle.

**
Major Arc
** -
An arc greater than 180 degrees.

**
Minor Arc
** -
An arc less than 180 degrees.

**
Point of Tangency
** -
The point of intersection between a
circle and its tangent line or tangent segment.

**
Radius
** -
A segment with one endpoint at the center of
a circle and the other endpoint on the circle.

**
Secant Line
** -
A line that intersects with a circle at
two points.

**
Sectors
** -
A region inside a circle bounded by a central angle and the minor arc
whose endpoints intersect with the rays that
compose the central angle.

**
Semicircle
** -
A 180 degree arc.

**
Tangent Line
** -
A line that intersects with a circle at
only one point (the point of tangency).

**
Tangent Segment
** -
A segment with one endpoint at the point of
tangency of a circle and the other endpoint on the tangent line.