| A | B |
|---|
| the set of all points outside a circle | exterior of a circle |
| a line that is in the same plane as a circle and intersects the circle at exactly one point | tangent of a circle |
| a segment whose endpoints lie on a circle | chord |
| the point of intersection of a circle or sphere with a tangent line or plane | point of tangency |
| a line that intersects a circle at two points | secant |
| a line that is tangent to two circles | common tangent |
| the set of all points inside a circle | interior of a circle |
| a segment of a secant that lies in the exterior of the circle with one endpoint on the circle | external secant segment |
| an angle whose vertex is on a circle and whose sides contain chords of the circle | inscribed angle |
| where the endpoints of a segment or arc lie on the sides of the angle | subtend |
| an angle whose vertex is the center of a circle | central angle |
| an arc of a circle whose points are on or in the exterior of a central angle | major arc |
| an unbroken part of a circle consisting of two points on the circle called the endpoints and all the points of the circle between them | arc |
| an arc of a circle whose points are on or in the interior of a central angle | minor arc |
| the distance along an arc measured in linear units | arc length |
| two arcs of the same circle that intersect at exactly one point | adjacent arcs |
| two arcs that are in the same or congruent circles and have the same measure | congruent arcs |
| a region inside a circle bounded by a chord and an arc | segment of a circle |
| two circles that have congruent radii | congruent circles |
| two coplanar circles that intersect at exactly one point | tangent circles |
| coplanar circles with the same center | concentric circles |
| an arc of a circle whose endpoints lie on a diameter | semicircle |
| a region inside a circle bounded by two radii of the circle and their intercepted arc | sector of a circle |
