The circumference of a circle is calculated using pi (π) and either the diameter or the radius of the circle.
Circumference Formulas
The circumference (C) can be found using one of two formulas:
- C = πd (where 'd' is the diameter of the circle)
- C = 2πr (where 'r' is the radius of the circle)
Explanation
- Diameter: The diameter of a circle is the distance across the circle through its center.
- Radius: The radius of a circle is the distance from the center of the circle to any point on its edge. The radius is half the diameter.
- Pi (π): Pi is a mathematical constant approximately equal to 3.14159. It represents the ratio of a circle's circumference to its diameter.
Examples
To find the circumference, you need to know either the diameter or the radius of the circle. Here are a couple of examples:
Example 1: Circle with a Diameter
If a circle has a diameter of 5 units, then its circumference is:
C = πd = π 5 ≈ 3.14159 5 ≈ 15.708 units.
Example 2: Circle with a Radius
If a circle has a radius of 3 units, then its circumference is:
C = 2πr = 2 π 3 ≈ 2 3.14159 3 ≈ 18.850 units.
In summary, the circumference is determined by multiplying pi by the diameter, or by multiplying 2, pi, and the radius.
