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• circle
• center
• radius
• chord
• diameter
• concentric circles
• circumference
• pi ()
• inscribed
• circumscribed
Identify Segments in a Circle
A. Name the circle and identify a radius.
Identify Segments in a Circle
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.
Find Radius and Diameter
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?
Find Measures in Intersecting Circles
Find Measures in Intersecting Circles
First, find ZY.
WZ + ZY = WY
5 + ZY = 8
ZY = 3
Next, find XY.
XZ + ZY = XY
11 + 3 = XY
14 = XY
Since the diameter of is 16 units, WY = 8. Similarly, the diameter of is 22 units, so XZ = 11. WZ is part of radius XZ and part of radius WY.
Find Measures in Intersecting Circles
Answer: XY = 14 units
A. 3 in.
B. 5 in.
C. 7 in.
D. 9 in.
Find Circumference
CROP CIRCLES A series of crop circles was discovered in Alberta, Canada, on September 4, 1999. The largest of the three circles had a radius of 30 feet. Find its circumference.
Since the radius is 30 feet, and d = 2r, the diameter = 2(30) or 60 feet.
C = d Circumference formula
= (60) Substitution
= 60 Simplify.
≈ 188.50 Use a calculator.Answer: The circumference of the crop circle is 60
feet or about 188.50 feet.
A. 377.0 feet
B. 392.5 feet
C. 408.3 feet
D. 422.1 feet
The Unisphere is a giant steel globe that sits in Flushing Meadows-Corona Park in Queens, New York. It has a diameter of 120 feet. Find its circumference.
Find Diameter and Radius
Find the diameter and the radius of a circle to the nearest hundredth if the circumference of the circle is 65.4 feet.
Circumference Formula
Substitution
Use a calculator.
Divide each side by .
Find Diameter and Radius
Answer: d ≈ 20.82 ft; r ≈ 10.41 ft
Radius Formula
Use a calculator.
A. 8.4 m
B. 5.35 m
C. 2.67 m
D. 16.8 m
Find the radius of a circle to the nearest hundredth if its circumference is 16.8 meters.
Assignment: pg 701-702 #10-38 EVENS only
----Then ask about making corrections to last time’s worksheet!
