Find the circumference of the circle with a radius of 8 cm.
Solution
Circumference = 2 * π* R = 2πR
= 2 * 3.14 * 8
= 50.24 cm.
Example 2
Calculate the circumference of a circle whose diameter is 70 mm
Solution
Circumference = π* D = π D
= 3.14 * 70
= 219.8 mm
Example 3
Calculate the perimeter of a circular flower garden whose radius is 10 m.
Solution
Circumference = 2 * π* R = 2πR
= 2 * 3.14 * 10
= 62.8 m.
Example 4
The circumference of a circle is 440 yards. Find the diameter and radius of the circle.
Solution
Circumference = 2 * π* R = 2πR
440 =2 * 3.14 * R
440 = 6.28R
Divide both sides by 6.28 to get,
R = 70.06
Therefore, the radius of the circle is 70.06 yards. But, since the diameter is twice the radius of a circle, the diameter is equal to 140.12 yards.
Example 5
The diameter of the wheels of a bicycle is 100 cm. How many revolutions will each wheel make to travel a distance of 157 meters?
Solution
Calculate the circumference of the bicycle’s wheel.
Circumference = π D
= 3.14 * 100
= 314 cm
To get the number of revolutions of the wheel, divide the distance covered by the circumference of the wheel.
We need to convert 157 meters to cm before dividing, so we multiply 157 by 100 to get 15700 cm. Therefore,
Number of revolutions = 15700 cm/314 cm
= 50 revolutions.
Example 6
A piece of a wire in the form of a rectangle of length 100 cm and width 50 cm is cut and folded to make a circle. Calculate the circumference and radius of the circle formed.
Solution
The circumference of the circle formed = the perimeter of the rectangular wire.
Perimeter of a rectangle = 2(L + W)
= 2(100 + 50) cm
= 2 * 150 cm
= 300 cm.
Therefore, the circumference of the circle will be 300 cm.
Answers & Comments
Answer:
C = π* D = π D
Step-by-step explanation:
Example 1
Find the circumference of the circle with a radius of 8 cm.
Solution
Circumference = 2 * π* R = 2πR
= 2 * 3.14 * 8
= 50.24 cm.
Example 2
Calculate the circumference of a circle whose diameter is 70 mm
Solution
Circumference = π* D = π D
= 3.14 * 70
= 219.8 mm
Example 3
Calculate the perimeter of a circular flower garden whose radius is 10 m.
Solution
Circumference = 2 * π* R = 2πR
= 2 * 3.14 * 10
= 62.8 m.
Example 4
The circumference of a circle is 440 yards. Find the diameter and radius of the circle.
Solution
Circumference = 2 * π* R = 2πR
440 =2 * 3.14 * R
440 = 6.28R
Divide both sides by 6.28 to get,
R = 70.06
Therefore, the radius of the circle is 70.06 yards. But, since the diameter is twice the radius of a circle, the diameter is equal to 140.12 yards.
Example 5
The diameter of the wheels of a bicycle is 100 cm. How many revolutions will each wheel make to travel a distance of 157 meters?
Solution
Calculate the circumference of the bicycle’s wheel.
Circumference = π D
= 3.14 * 100
= 314 cm
To get the number of revolutions of the wheel, divide the distance covered by the circumference of the wheel.
We need to convert 157 meters to cm before dividing, so we multiply 157 by 100 to get 15700 cm. Therefore,
Number of revolutions = 15700 cm/314 cm
= 50 revolutions.
Example 6
A piece of a wire in the form of a rectangle of length 100 cm and width 50 cm is cut and folded to make a circle. Calculate the circumference and radius of the circle formed.
Solution
The circumference of the circle formed = the perimeter of the rectangular wire.
Perimeter of a rectangle = 2(L + W)
= 2(100 + 50) cm
= 2 * 150 cm
= 300 cm.
Therefore, the circumference of the circle will be 300 cm.
Now calculate its radius.
Circumference = 2 π R
300 cm = 2 * π * R
78.5 cm
105 m
300 sq.m