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# Finding the Radius from the Area

(KS3, Year 7)

## The Lesson

The radius of a circle is found from the area of a circle using the formula:In this formula,

**A**is the area of the circle. The image below shows what we mean by finding the radius from the area:

## How to Find the Radius from the Area

Finding the radius from the area is easy.## Question

What is the radius of the circle, with area 10 cm^{2}, below?

## Step-by-Step:

# 1

Start with the formula:

Radius = √ (

^{A}⁄_{π})**Don't forget:**√ means square root, / means ÷**and**π is pi (≈ 3.14)# 2

Substitute the area into the formula. In our example, A = 10.

Radius = √ (

^{10}⁄_{π}) Radius = √ (10 ÷ π) Radius = √ (10 ÷ 3.14) Radius = √ 3.18 Radius = 1.78 cm## Answer:

The radius of the circle is 1.78 cm.## Interactive Widget

Here is an interactive widget to help you learn about finding the radius of a circle from its area.**Help Us To Improve Mathematics Monster**

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