Circle Calculator

Circle Calculator

Choose a value to calculate: Radius Diameter Circumference Area
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Radius:
Diameter:
Circumference:
Area:

What is a Circle?

A circle is a two-dimensional geometric shape that is defined as the set of all points in a plane that are equidistant from a fixed point called the center. The distance from the center to any point on the circle is called the radius. Alternatively, the diameter of a circle is twice the radius, and it is the distance across the circle through its center.

Circle Equation

Equation:

Finding Radius, Diameter and Circumference of a Circle

Radius (r)

The radius is the distance from the center of the circle to any point on its circumference.

Formula:

​,

where d is the diameter.

Diameter (d):

The diameter is the distance across the circle through its center.

Formula:

where r is the radius

Circumference (C):

The circumference is the total length around the circle.

Formula:

where π is a constant approximately equal to 3.14159, and r is the radius.

Getting the Area of a Circle

The area (A) of a circle can be calculated using the formula:

Where:

• A is the area of the circle.
• π is a mathematical constant approximately equal to 3.14159.
• r is the radius of the circle.

To find the area of a circle, follow these steps:

1. Measure or determine the radius (r) of the circle.
2. Substitute the value of r into the formula A=πr².
3. Calculate the square of the radius (r²).
4. Multiply the result by the constant π to get the area (A).

A = π * (5 units)²
A= 3.14159 * 25
A = 78.54square units