| A | B |
|---|
| Diameter | A chord that contains the center of a circle. |
| Center | Middle of a circle. |
| Point of Tangency | Point where a tangent line touches a circle. |
| Congruent Circles | They have congruent radii. |
| Chord | A segment whose endpoints lie on a circle. |
| Circle | The set of points in a plane at a given distance from a given point in that plane. |
| Tangent | A line that intersects the circle in exactly one point. |
| Concentric Circles | They have the same center. |
| Secant | A line that contains a chord. |
| Radius | Any segment that joins the center to a point on the circle. |
