Term

Definition
the set of all points in a plane that are equidistant from a given point 


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Definition
The set of all points in a plane that are equidistant from a given point, called the center of the circle. 


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Definition
The distance from the center of a circle to a point on the circle. A segment whose endpoints are the center of the circle and a point on the circle. Plural is radii. 


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Definition
Two circles that have the same radius. 


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Definition
A chord that passes through the center of the circle. The distance across a circle, through its center. 


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Definition
a segment whose endpoints are points on the circle. PS A and PR Aare chords. 


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Definition
a line that intersects a circle in two points. Line j is a secant. 


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Definition
A trigonometric ratio, abbreviated as tan; a line in the plane of a circle that intersects the circle in exactly one point. 


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Definition
Circles that intersect in one point 


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Definition
Circles that have a common center. 


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Definition
A line or segment that is tangent to two circles. A common internal tangent intersects the segment that joins the centers of the two circles. A common external tangent does not intersect the segment that joins the centers of the two circles. 


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Definition
All points of the plane that are inside a circle. 


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Definition
All points of the plane that are outside a circle. 


Term
[image] point of tangency 

Definition
The point at which a tangent line intersects the circle to which it is tangent is the point of tangency. 


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Definition
An angle whose vertex is the center of a circle. 


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Definition
Part of a circle that measures between 180° and 360°. 


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Definition
Part of a circle that measures less than 180°. 


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Definition
An arc whose endpoints are the endpoints of a diameter of the circle. 


Term
[image] measure of a minor arc 

Definition
The measure of its central angle. 


Term
[image] measure of a major arc 

Definition
The difference between 360° and the measure of its associated minor arc. 


Term

Definition
An angle whose vertex is on a circle and whose sides contain chords of the circle. 


Term

Definition
The arc that lies in the interior of an inscribed angle and has endpoints on the angle. 


Term

Definition
An angle whose vertex is on a circle and whose sides contain chords of the circle. 


Term

Definition
If a line is tangent to a circle, then it is perpendicular to the radius drawn to the point of tangency. 


Term

Definition
In a plane, if a line is perpendicular to a radius of a circle at its endpoint on the circle, then the line is tangent to the circle. 


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Definition
If two segments from the same exterior point are tangent to a circle, then they are congruent. 


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Definition
The measure of an arc formed by two adjacent arcs is the sum of the measures of the two arcs. 


Term

Definition
In the same circle, or in congruent circles, two minor arcs are congruent if and only if their corresponding chords are congruent. 


Term

Definition
If a diameter of a circle is perpendicular to a chord, then the diameter bisects the chord and its arc. 


Term

Definition
If one chord is a perpendicular bisector of another chord, then the first chord is a diameter. 


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Definition
In the same circle, or in congruent circles, two chords are congruent if and only if they are equidistant from the center. 


Term

Definition
If an angle is inscribed in a circle, then its measure is half the measure of its intercepted arc. 


Term

Definition
If two inscribed angles of a circle intercept the same arc, then the angles are congruent. 


Term

Definition
If a right triangle is inscribed in a circle, then the hypotenuse is a diameter of the circle. Conversely, if one side of an inscribed triangle is a diameter of the circle, then the triangle is a right triangle and the angle opposite the diameter is the right angle. 


Term

Definition
A quadrilateral can be inscribed in a circle if and only if its opposite angles are supplementary. 

