Vocabulary
A straight line from the center to the circumference of a circle or sphere
Radius
What is the area of a circle if:
the Radius = 6 in
113.04 in2
6 * 6 * 3.14
36 pi or 113.04
What is the circumference of a circle if:
the radius = 7 yds?
43.96yds
When I need a circumference Ill just use pi d.
radius = 7
7 * 2 = 14
14 is diameter
14 * pi is 14 pi or 43.96
What is the formula to find the area of a circle?
A=
pir^2
What is the diameter of a circle whose circumference is 314?
100
314 / 3.14
Name the line in a circle that cuts it in half.
Diameter
A diameter goes across the circle passing through the middle.
What is the area of a circle if:
the Radius = 3 ft
28.26 ft2
3 * 3 * 3.14
What is the circumference of a circle if:
the radius = 9 yds?
56.52yds
radius = 9
9 * 2 = 18 which is the diameter
18 * pi is circumference or 18 * 3.14
18pi or 56.52
What is the decimal approximation we use for pi?
3.14
What part of a circle is needed to find the AREA?
Radius
The outside measurement of a circle. Or the distance around the outside of the circle
Circumference
Circumference is the perimeter of a circle.
The diameter of a circle is 6 ft.
Find its area in terms of π.
9π ft2
6/2 = 3
3 * 3 * π= 9π
The radius of a circle is 7 m. Find its circumference in terms of π.
14π
Find the area of a circle when the circumference is 28.26 feet.
63.59 ft2
28.26 / 3.14 = 9 This is the diameter
9/2 = 4.5 this is the radius
4.5 * 4.5 * 3.14 = 63.585
What is the radius of a circle whose circumference is 901?
14.49
901 / 3.14 =28.98
28.98 / 2 = 14.49
The measurement of the inside of a circle. Or how much the circle covers
Area
The circumference of a circle is 8π cm.
What is the area, in square centimeters? Express your answer in terms of π.
16π cm2
8/2 = 4
4 * 4 * π
The circumference of a circle is 2π m. Find its diameter, in meters.
2 meters
A Ferris wheel has a diameter of 80 meters. How many meters does a rider travel in THREE complete rotations around the Ferris wheel? Round to the nearest tenth
753.6 meters
80 /3.14 = 251.2 Circumfence (1 rotation)
251.2 * 3 = 753.6
What is circumference?
A. The distance around a circle.
B. The space inside the circle.
C. line from side to side passing through the center.
D. line from the center to the side.
A. The distance around a circle.
Circumference divided by diameter.
Pi - 3.14
A dog is leashed to a point in the center of a large yard, so the area the dog is able to explore is circular. The leash is 20 feet long. What is the area of the region the dog can explore?
1256
r = 20
20 * 20 * 3.14
The circular fountain in front of the courthouse has a radius of 9.4 feet. What is the circumference of the fountain to the nearest foot?
59
9.4 * 2 = 18.8
18.8 * 3.14 = 59.032
Which rounds to 59.
A rose garden is circular. How much space does the rose garden take up if the diameter of the garden is 18 feet? (use 3.14 for pi)
254.34 ft2
18 /2 = 9 this is the radius
9 * 9 * 3.14
254.34
What is the radius of a circle with a circumference of 368.636
58.7