How to Find the Radius of a Circle: Formulas and Examples

Radius

The radius of a circle is a line segment that connects the center of the circle to any point on the circumference

The radius of a circle is a line segment that connects the center of the circle to any point on the circumference. It is the distance between the center and any point on the circle.

To find the radius of a circle, you need to know either the diameter or the circumference of the circle.

If you know the diameter, which is the distance across the circle passing through the center, you can find the radius by dividing the diameter by 2. In equation form, this can be written as:

Radius = Diameter / 2

For example, if the diameter of a circle is 10 units, the radius would be 10/2 = 5 units.

If you know the circumference, which is the distance around the circle, you can find the radius using the formula:

Radius = Circumference / (2 * pi)

Here, pi is a mathematical constant approximately equal to 3.14159.

For example, if the circumference of a circle is 20 units, the radius would be 20 / (2 * 3.14159) = 3.183 units (rounded to three decimal places).

Alternatively, if you only have the area of the circle, you can find the radius using the formula:

Radius = Square root of (Area / pi)

Here, pi represents the mathematical constant mentioned earlier.

For example, if the area of a circle is 25 square units, the radius would be the square root of (25 / 3.14159) = 2.82 units (rounded to two decimal places).

Remember to label the units when expressing the radius. The radius is always half the length of the diameter and is always measured in the same units as the diameter.

I hope this helps clarify the concept of radius and how to find it!

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