Circles

Circle

A plane figure enclosed by curve such that all the points on the curve are of the same distance from a fixed point.

Fixed point

Called the center of the circle.

Circumference

The curve of the circle.

Chord

A line segment joining any two points on the circumference.

Diameter

A chord passing through the center. Is also the longest line in a circle.

Radius

A line segment joining the circle a point on the circumference.

Tangent

Exactly intersects a circle at one point.

Secant

Extended chords.

Arc

A portion of the circumference.

Minor arc

Less than 180 degrees.

Major arc

More than 180 degrees.

Segment

Enclosed by a chord and an arc.

Semi-circle

Enclosed by a diameter and an arc.

Sector

Bounded by two radii and an arc.

Central angle

Angle which vertex is at the center.

Inscribed angle

Angle which vertex is on the circle.

Equal circle

if the radii(or diameter) of two circles are equal.

Concentric circle

Same center.

Intercepted arc

Is equal to the measurement of a central angle.

360 degrees

Is the sum of all the measures in a circle.