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Section 10-1. Tangents to Circles. Center. P. Circle. The set of all points in a plane that are equidistant from a given point ( center ). Circles are named by their center!. Circle P. Interior of a circle. Consists of the points inside the circle. Exterior of a circle.
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Section 10-1 Tangents to Circles
Center P Circle • The set of all points in a plane that are equidistant from a given point (center). Circles are named by their center! Circle P
Interior of a circle • Consists of the points inside the circle Exterior of a circle • Consists of the points outside the circle
L A N G E P
P Radius Radius • The distance from the center of a circle to a point on the circle
Radius • Segment whose endpoints are the center of the circle and a point on the circle • All radii of a circle are congruent!
Chord • A segment whose endpoints lie on a circle
Diameter Diameter • The distance across the circle, through the center • The diameter is twice the radius
Secant Secant • A line that intersects a circle in two points. • It goes through the circle!
tangent • A line in the plane of a circle that intersects the circle in exactly one point, called the point of tangency.
Tangent Line Point of Tangency
Circle P Chord Diameter P Secant
Common tangent • A line or segment that is tangent to two coplanar circles
A B Common internal tangent • Intersects the segment that joins the centers of two circles
B A Common external tangent • Does NOT intersect the segment that joins the centers of two circles.
In a plane, two circles can intersect in two points, one point, or no points.
Concentric circles • Circles that lie in the same plane and have the same center