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Circle

A shape consisting of those points in a plane which are equidistant from a given point called the center.

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Pi (π)

The ratio of the circumference to the diameter of a circle.

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Radius

A line from the center of the circle of the circle to any point on the circle.

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Radii

more than 1 radius.

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Chord

A line segment that links 2 points on a circle.

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Diameter

A chord that crosses through the center of the circle.

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Tangent

A line or ray that interests a circle at only 1 point.

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Point of Tangency

The point where a circle and a tangent intersect.

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Arc

Part of a circle with an angle measure.

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Minor Arc

Arc whose measure is smaller than 180 degrees.

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Major Arc

Arc whose measures is larger than 180 degrees.

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Semi-circle

Arc whose measure is equal to 180 degrees.

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Central Angle

An angle whose vertex is a center of a circle.

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Congruent Circles

Circles with congruent radii.

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