| A | B |
|---|
| radius | the distance from the center to a point on the circle |
| circle | a set of coplanar points a given distance from a given point |
| chord | a segment connecting two points on a circle |
| diameter | a segment connecting two points on a circle and passing through the center |
| secant | a line passing through two points on a circle |
| tangent | a line touching a circle in exactly one point |
| central angle | an angle having its vertex at the center of the circle |
| inscribed angle | an angle having its vertex on the circle whose sides are chords of the circle |
