Section 7.1 -- Circles
Definitions:
Circle: the set of all points in the same plane that are a fixed distance from a point called
its center
Radius: a line segment drawn from the center of a circle to one of the points on the circle
Chord: a line segment connecting two points on a circle
Diameter: a chord that passes through the center of a circle
Tangent: a line that has exactly one point of intersection with a circle
Point of Tangency: the point of intersection between a circle and a tangent
Arc: a continuous portion of a circle
Semicircle: an arc of a circle whose endpoints are endpoints of a diameter of a circle
Major Arc: an arc that is greater than a semicircle
Minor Arc: an arc that is less than a semicircle
Congruent Circles: two or more circles with congruent radii
Central Angle: an angle whose vertex is at the center of a circle and whose sides are radii
of the circle
Measure of an Arc: equal to the number of degrees in the central angle that intercepts the arc
Congruent Arcs: two arcs in the same circle or congruent circles that have the same
measure
Definition of Betweenness for Arcs: If A, B, and C are three points on the same arc, and B is
between A and C, then
p
p
p
mAC mAB mBC=+ or any equivalent statement.
Inscribed Angle: an angle whose vertex is on a circle and whose sides are chords of the
circle
Secant: a line that intersects a circle in two points
