Lesson 8 1 Circle Terminology 1 Circle Definition

Lesson 8 -1 Circle Terminology 1

Circle Definition Circle : The set of points coplanar points equidistant from a given point. The given point is called the CENTER of the circle. The distance from the center to the circle is called the RADIUS. Center Radius 2

Definitions Chord : The segment whose endpoints lie on the circle. Diameter : A chord that contains the center of the circle. Tangent : A line in the plane of the circle that intersects the circle in exactly one point. Tangent Point of Tangency : ord h C The point where the tangent line intersects the circle. Secant : A line that contains a chord. Diameter Secant 3

Example: In the following figure identify the chords, radii, and diameters. B Chords: C A O Radii: D F E Diameter: 4

Definitions Congruent Circles : Circles that have congruent radii. 2 2 Concentric circles : Circles that lie in the same plane and have the same center. 5

Polygons Inscribed Polygon: A polygon inside the circle whose vertices lie on the circle. Circumscribed Polygon : A polygon whose sides are tangent to a circle. 6

ARCS Arcs : The part or portion on the circle from some point B to C is called an arc. B Example: Semicircle: A B An arc that is equal to 180°. A Example: C O C 7

Minor Arc & Major Arc Minor Arc : A minor arc is an arc that is less than 180° A minor arc is named using its endpoints with an “arc” above. A Example: Major Arc: A major arc is an arc that is greater than 180°. B A major arc is named using its endpoints along with another point on the arc (in order). O C Example: 8

Example: ARCS Identify a minor arc, a major arc, and a semicircle, given that is a diameter. Minor Arc: E D A Major Arc: C F Semicircle: 9

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