geometry

Circle

the set of all points in a plane that are equidistant from the same given point

Radius

a segment with one endpoint on the circle and the other endpoint at the center of the circle

Diameter

a segment with both endpoints on the circle that goes through the center of the circle; a chord going through the center of the circle

Circumference

the distance around the outer edge of the circle

Pi

the ratio of every circle's circumference length to its diameter length

Central angle

an angle formed by 2 radii with the vertex at the center of the circle

Intercepted arc

the part of a circle that lies between two segments that intersect the circle

Minor arc

An arc with a measure less than 180

Major arc

An arc with a measure more than 180

Semi circle

An arc whose endpoints are on the diameter; half a circle

Arc length

the measurable distance between the endpoints along a circle's arc; a portion of the circle's circumference

Sector area

The area bounded by two radii and their intercepted arc

Segment area

The area bounded by the segment jointing two radii endpoints and their intercepted arc

Tangent line

A line that never enters the circle, making contact at exactly one point

Point of tangency

The point where a tangent line makes contact with the circle

Chord

A segment whose endpoints lie on a circle

Inscribed angle

An angle whose vertex and endpoints are all on the circle; the sides of the angle are chords

Secant

A line or ray going through the circle,making contact with the circle at two different places