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.