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Perimeter of a Circle Formula
The perimeter of a circle formula is used to find the perimeter of a circle. The perimeter of a circle is its boundary or the complete arc length of the periphery of a circle. The term that denotes the perimeter of a circle is called its circumference. Hence the perimeter of a circle tells us about the circumference of a circle; therefore, it is also known as the circumference of a circle formula.
What Is the Perimeter of a Circle Formula?
The perimeter of a circle formula has three components, two constants and one variable. The formula to calculate the perimeter of a circle or circumference formula can be given as:
The perimeter of a circle = 2 π r
= π D units
where,
r = radius of the circle
D = diameter of the circle
Examples of Perimeter of Circle Formula
Let us solve some interesting problems using the perimeter of the circle formula.
Example 1: Using the perimeter of a circle formula, calculate the circle’s circumference with a diameter of 7 in (Use the value of π as 22/7)?
Solution:
To find: Perimeter of a circle
Given: Diameter of circle = 7 in
Using the perimeter of a circle formula,
The perimeter of a circle = π D
Perimeter or circumference = 22/7 × 7
= 22 in
Answer: Perimeter of circle or circumference = 22 in.
Example 2: Using the perimeter of a circle formula, find the circle’s radius circumference of 110 in.
Solution:
To find: Radius of circle
Given: Circumference = 110 in
Using the perimeter of a circle formula,
The perimeter of the circle or circumference = 2π r
2 π r = 110
2 × 22/7 × r = 110
r = 110 × 7 / 44
r = 17.5
Answer: Radius of circle = 17.5 in.
Example 3: The radius of a circle is 7 in. Using the perimeter of a circle formula, calculate the circle’s circumference.
Solution:
To find: Perimeter of circle
Given: r = 7 in
The perimeter of circle formula = 2 π r
C = 2 × (22/7) × (7)
Answer: The circumference of a circle is 44 inches
