| A | B |
|---|
| Circle | Set of all points in a plane that are equidistant from a given point (center) |
| Radius | Distance from center to a point on the circle |
| What makes circle Congruent? | If they have the same radius |
| Diameter | Distance across a circle, through its center; diameter is twice the radius |
| Chord | Segment whose endpoints are points on the circle; diameter is a chord that passes through the center |
| Secant | Line that intersects a circle in 2 points |
| Tangent | Line that intersects a circle in exactly one point |
| Point of tangency | Point where a tangent line intersects a circle; if a line is a tangent to a circle, then it is perpendicular to the radius drawn to the point of tangency |
| Concentric Circles | Coplanar circles that have a common center |
| Theorem-tangents | If RP and RQ are tangent to circle C, then RP is congruent to RQ |
| Central Angle | Angle whose vertex is center of the circle |
| Arc | Unbroken part of a circle |
| Minor Arc | Part of a circle that measures less than 180 degrees |
| Major Arc | Part of a circle that measures between 180 and 360 degrees |
| Semicircle | Arc whose end points are the end points of a diameter (half circle) |
| Inscribed Angle | Angle whose vertex is on a circle and whose sides are made up of chords of the circle |
| Intercepted Arc | Arc that lies in the interior of an inscribed angle |
| 1st circle property | If 2 interscribed angles intercept the same arc, then the 2 angles are congruent |
| 2nd circle property | Measure of the angle formed by the tangent and chord equals one half the intercepted arc |
| 3rd circle property | An inscribed angle formed with endpoints of a diameter will always create a right angle |
| 4th circle property | A quadrilateral can be inscribed in a circle iff its opposite angles are supplementary |
| 5th circle property | 2 congruent chords are equidistant to the center |
