Circle Geometry Terms

Front

Circle

Back

The set of points equidistant from a given point (the center).

Front

Radius

Back

A segment with endpoints at the center and on the circle.

Front

Diameter

Back

A chord that passes through the center. Diameter = 2 times (multiplication) radius.

Front

Secant

Back

A line that intersects the circle in exactly two places.

Front

Tangent

Back

A line that intersects the circle at exactly one place.

Front

Inscribed Angle

Back

An angle with a vertex on the circle, and two sides that are chords.

Front

Minor Arc

Back

An arc with a measure less than 180°. Use 2 letters to name it.

Front

Major Arc

Back

An arc with a measure greater than 180°. Use 3 letters to name it.

Front

Semicircle

Back

An arc with endpoints on the diameter. Always equals 180°.

Front

Circumference of a Circle (using radius)

Back

C = 2 πr (r = radius)