10-1circles and circumference you identified and used parts of parallelograms. identify and use...
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10-1Circles and Circumference
You identified and used parts of parallelograms.
• Identify and use parts of a circle.
• Solve problems involving the circumference of a circle.
Definition
A circle is the locus of points in a plane equidistant from a given point.
That point is the center of the circle.
center
Circle Parts
A circle is named by its center.
A radius is a segment from the center to any point on the circle.
A diameter is a segment that contains the center of the circle and has endpoints on the circle.
Qּס
Qּס
radius
diameter
Definition
A chord is a line segment that joins two points on a circle.
AB is a chord of ּסD
Where would you find the largest chord in any circle?
A
B
D
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A. Name the circle and identify a radius.
B. Identify a chord and a diameter of the circle.
A. Name the circle and identify a radius.
A.
B.
C.
D.
B. Which segment is not a chord?
A.
B.
C.
D.
By definition, the distance from the center of a circle to any point on the circle is always the same. All radii of a circle are congruent. A diameter (d) is made is made up of two radii.
1 raduis 1 raduis
p. 698
Answer: QV = 10.5 cm
d = 2r Diameter Formula
21 = 2r d = 21
10.5 = r Simplify.
If RT = 21 cm, what is the length of QV?
RT is a diameter and QV is a radius.
A. 12 cm
B. 13 cm
C. 16 cm
D. 26 cm
If QS = 26 cm, what is the length of RV?
Exterior, Interior, Concentric
interior
exterior
Concentric circles are two coplanar circles with the same center.
p. 698
5
A. 3 in.
B. 5 in.
C. 7 in.
D. 9 in.
10-1 Assignment Day 1
p. 701, 10-21