With this calculator you can easily know the area of a circle or circumference from several variables, such as: Radius, Diameter or Length of the circumference.

In addition to the calculator you will find 3 different ways to calculate the area of a circle and many practical examples.

## Formulas to calculate the area of a circle:

**1. Formula to calculate area of a circle from the radius:** To make this calculation you must have the radius of the circle and with the following formula:**Where:**

**A: Area of the circle****π: Constant Number equivalent to 3.1415****A: Circle radius**

**2. How to calculate the area of a circle when you have the diameter:** For this calculation you must have the diameter of the circle and then enter it in the following formula:

**Where:**

**A: Area of the circle****π: Constant Number equivalent to 3.1415****D: Diameter of the circle**

**3. Finally, there is the formula for calculation of Area from the length of the circumference:** This formula facilitates the calculation of the area when you count with the length of the circumference.

**Where:**

**AR: Circle radio****π: Constant Number equivalent to 3.1415****LC: Length of the circumference.**

## Examples of use for formulas for calculating the area:

**Example 1: A pizza has a radius of 20cm. What is the area of the pizza?**

Solution:

We take the formula from radio to area and replace the value of the radius in the following way: **A = πx20cm ^ 2, the result will be: 31,83cm ^ 2**

**Example 2: The rim of a Mazda 2 car has a diameter of 16 “. What is the area of this tire?**

From the formula of diameter to area, we can replace the diameter in this formula, being as follows: **A = (πx16 “^ 2) / 4, the result will be: 20.37” ^ 2**

**Example 3: The pipe of an aqueduct has a circumference length of 34cm. What will be the area of the pipe?**

To calculate the area you must enter the value of the circumference length in the corresponding formula, as I show below: **A = (34cm ^ 2) / πx4, the result will be: 91,99cm ^ 2**

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