Name Block
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Circle
Parts of a Circle
Term
Chord
Definition
Radius
Diameter
Ex. 1 Identifying Parts of a Circle a) Name the circle. b) Name all the radii (plural of radius) of the circle. c) Name all of the chords of the circle. d) Name the diameter of the circle.
Example Picture

Ex. 2 Identifying Parts of a Circle a) Name the circle. b) Name all the radii (plural of radius) of the circle. c) Name all of the chords of the circle. d) Name the diameter of the circle.
Important Facts About Circles
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All radii in a circle are ____________________.
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The radius (r) is _______________ of the diameter (d).
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The diameter (d) is _______________ of the radius (r).
Ex. 3 Radius and Diameter a) If DF = 10, find DA. b) If PA = 7, find PG. c) If AG = 12, find LA.

Ex. 4 Finding Measures in Intersecting Circles
The diameters of circle A, B, and C are 10 inches, 20 inches and, 14 inches respectively. a) Find XB. b) Find BY. c) Find XY.
Ex. 5 Finding Measures in Intersecting Circles
The diameters of circle X, Y, and Z are 22 feet, 16 feet, and 10 feet respectively. a) Find EY. b) Find EZ. c) Find XF.

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Circumference
 There are two formulas that we can use to find the circumference of a circle:
1) ____________________
2) ____________________
 If you know the diameter or radius, you can find the circumference of a circle. Likewise, if you know the circumference, you can find the diameter or radius.
Ex. 6 Relationships Between Circumference, Diameter, and Radius
Directions: Round all answers to the nearest tenth. a) Find C if r = 7 centimeters. b) Find C if d = 12.5 inches. c) Find d if C = 135 meters. d) Find r if C = 95 meters.

e) Find C if d = 24 feet. f) Find d if C = 50 inches.
Ex. 7 Using Other Figures to Find Circumference
Directions: Round all answers to the nearest tenth. a) Find the circumference of circle P. b) Find the circumference of the circle to the right.