| A | B |
|---|
| arc | a part of a circle |
| congruent arcs | arcs that have the same meaure AND are in the same or congruent circles |
| central angle | angle whose vertex is the center of a circle |
| circle | set of points in a plane that are equidistant from a given point |
| chord | segment that has both endpoints on the circle |
| concentric circles | circles that are coplanar and have the same center |
| congruent circles | circles that have congruent radii |
| circle circumscribed about a polygon | circle that has contains all the vertices of a polygon |
| circle inscribed in a polygon | circle that has sides of a polygon as tangent lines |
| diameter | chord that contains the center |
| radius | segment whose endpoints are the center of the circle and a point on the circle |
| secant | line that intersects a circle in exactly two points |
| semicircle | arc with measure exactly 180 degrees |
| tangent | line that intersects a circle in exactly one point |
