﻿ Circle - radius: - on line calculation, formula - FORMIAX ﻿

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# Circle (with radius) - perimeter and area

P = 2 πr

A = πr2

A = area

P = Perimeter

d = diameter

## WHAT IS IT ?

A circle is a two-dimensional shape consisting of all points in a plane that are at a given distance, called the radius, from a fixed point known as the center. The properties of a circle include the perimeter, which is the distance around the circle, and the diameter, which is twice the length of the radius and passes through the center. All radii in a circle are equal in length. Circles are fundamental shapes in geometry and have various applications in mathematics, design, engineering, and nature.

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## CALCULATION:

Enter unit e.g.: inch

Enter the number of decimal places

## EXAMPLE:

Let's assume we have a circle with a radius of r = 7 cm.

### Calculation of the perimeter

The perimeter C is calculated using the formula:

C = 2 · π · r

Since π ≈ 3.14159, we can calculate the perimeter:

C = 2 · 3.14159 · 7

C = 43.98226 cm

### Calculation of the area

The area A is calculated using the formula:

A = π · r^2

Now we can calculate the area:

A = 3.14159 · 7^2

A = 3.14159 · 49

A = 153.93804 cm²

### Summary

Radius of the circle: r = 7 cm

Circumference of the circle: C ≈ 43.98226 cm

Area of the circle: A ≈ 153.93804 cm²

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