Congruent Circle

A circle that is congruent radii.

Diameter

A line segment that goes from one side of the circle to another passing through the center.

Central Angle

An angle that whose vertex is in the center of a circle.

Semicircle

Half of a circle.

Minor Arc

Minor Arc- An arc with the angle measure less than 180

Major Arc

Major Arc- An arc with the angle measure greater than 180

Adjacent Arcs

The arcs of the same circle that have exactly one point in common.

Concentric Circles

Circles that lie on the same plane and have the same center.

Arc Length

A fraction of the circle's circumference.