Circles.notebook
March 21, 2017
Warm-Up
A
E
Wednesday 3-15
126O
B
(4x + 34)O
D
C
1. What is the equation used to solve for the variable?
2. What is the value of x?
3. Name an angle adjacent to <ABC. 1
Circles.notebook
March 21, 2017
:
set of points that are the
same distance from a
given point
distance from the center
to any point on the circle
: distance across a circle
through the center
: distance around the circle
(the perimeter)
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Circles.notebook
March 21, 2017
circumference
diameter
3.1415926...
remember pi is an irrational number!
http://alyten.com/videos/pi­explained­in­3­minutes­and­14­seconds/
OR
https://www.youtube.com/watch?v=8­cazxAL_tU
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Circles.notebook
March 21, 2017
Important Formula Alert!!!!
two???
e
r
e
h
t
Why are
d = r*2
r=d÷2
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Circles.notebook
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Textbook Practice
Textbook p. 560 #8-18 (even)
Textbook p. 565 #8-18 (even)
Finish For Homework
7
Circles.notebook
Warm-Up
March 21, 2017
Thursday 3-16
1. A basketball goal is 18 inches in diameter. A basketball has a diameter of about 9.6 inches. What is the difference in circumference between the goal and the center cross­section of a basketball?
2. The standard trampoline has a circumference of about 41 feet. When Jenna’s dad lays with his feet at the center of the trampoline, the top of his head aligns with the outer edge. About how tall is Jenna’s dad? 8
Circles.notebook
March 21, 2017
HW Check
Textbook p. 560 #8-18 (even)
Textbook p. 565 #8-18 (even)
8. 6.3 cm
8. 50.3 cm2
10. 50.3 in
10. 78.5 mi2
12. 39.0 km
12. 66.5 cm2
14. 86.1 mm
14. 289.5 ft2
16. 45.9 yd
16. 103.9 yd2
18. 1729 km
18. 804.2 cm2
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Circles.notebook
March 21, 2017
Circle Question Set #1
1. What is the radius of a circle if the diameter is 18 in? 9 in
Match each circle with its circumference.
A
A. 53.4 cm
3. diameter = 9 cm C
B. 20.4 cm
4. radius = 12 cm
C. 28.3 cm
2. radius = 8.5 cm
D
D. 75.4 cm
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2 A B C D 12
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3 A B C D 13
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4 A B C D 14
Circles.notebook
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Circle Questions Set #2
Find the area. Round to the nearest tenth. 1. diameter = 9 kilometers 63.6 km2
2. radius = 7.2 feet 162.8 ft2
3. The spray from a rotating sprinkler makes a circle with a 20­foot diameter. What area of a yard does the water from the sprinkler cover? Round to the nearest whole number. 314 feet2
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3 18
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