adjacent arcs
arcs in a circle that have exactly one point in common
arc
a part of the circle that is defined by 2 endpoints
center
the central point where radii form a set of points called a circle
central angle
an angle that intersects a circle in 2 points and has its vertex at the center of the cirlce
chord
a segment with 2 endpoints on the cirlce
circle
the set of all points in a plane equidistant from a given point called a center
circumference
the distance around the circle. also refer to as the perimeter of the circle
circumscribed
a circle is circumscribed about a polygon if the circle contains all vertices of the polygon
concentric circles
coplanar circles with different sizes, and the same center
diameter
a chord that passes through the center of the circle
external segment
a segment that lies on the exterior of the circle
inscribed
a polygon is inscribed in a circle if each of its vertices lie on the circle
inscribed angle
an angle that has a vertex on a circle and sides that contain chords of the circle
intercepted arc
an arc that has endpoints on the sides of an inscribed angle and lies in the interior of the inscribed angle
major arc
an arc that has a measure greater than 180 degress
minor arc
an arc that has a measure of less than 180 degrees
point of tangency
for a line that interesects a circle in only on point, at which they intersect
radius
a segment that has an endpoint at the center and on the circumference of the circle
secant
a line that intersects a circle at 2 points
semicircle
an arc that measures exactly 180 degrees
tangent
a line that intersects a circle at 1 point