The image above is a circle.

To compute the area of a circle, one essential parameter is needed and this parameter is the **radius of a circle** (r). You can also use the **diameter of a circle** to compute the area of a circle (d).

The formula for calculating the area of a circle is:

A = πr^{2}

Where:

A = Area of a circle

r = Radius of a circle

Let’s solve an example:

Find the area of a circle where the radius of a circle is 6 cm.

This implies that;

r = Radius of a circle = 6 cm

A = πr^{2}

A = 3.142 (6)^{2}

A = 3.142 (36)

A = 113.10

Therefore, the **area of a circle** is **113.10 cm ^{2}**

**Calculating the Area of a Circle using the Diameter of a Circle.**

The formula is A = ^{πd2}/_{4}

Where;

A = Area of a circle

d = Diameter of a circle

Let’s solve an example:

Find the area of a circle where the diameter of the circle is 7 cm.

This implies that;

d = Diameter of a circle = 4 cm

A = ^{πd2} / _{4}

A = ^{3.142 (4)2} / _{4}

A = ^{3.142 (16)} / _{4}

A = 3.142 (4)

A = 12.57

Therefore, the **area of a circle with diameter** **given **is **12.57 cm ^{2}**

**How to Calculate Radius of a Circle when Area of the Circle is Given**

r = √ (^{A} / _{π })

where;

r = Radius of a circle

A = Area of a circle

Let’s solve an example:

Find the radius of a circle where the area of the circle is 16 cm^{2}

This implies that;

A = Area of the circle = 16 cm^{2}

r = √ (^{A} / _{π})

r =√ (^{16} / _{π})

r = √ (^{16} / _{3.142})

r = √ (5.09)

r = 2.26

Therefore, the **radius of the circle** is** 2.26 cm.**

**How to Calculate Diameter of a Circle when Area of the Circle is Given**

d = √ (^{4A} / _{π})

where;

d = Diameter of a circle

A = Area of a circle

Let’s solve an example;

Find the diameter of a circle where the area of the circle is 20 cm^{2}

This implies that;

A = Area of the circle = 20 cm^{2}

d = √ (^{4A} / _{π})

d = √ (^{4(20)} / _{π})

d = √ (^{80} / _{π})

d = √ (^{80} / _{3.142})

d = √(25.46)

d = 5.046

Therefore, the** diameter of the circle** with area is **5.046 cm**.

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the area of a circle.

To get the answer and workings of the area of a circle using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **for** NGN 1,500 **per** annum** to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Mensuration**** **under the** Mathematics** section

Now, click on** Area of a Circle** under **Mensuration**

The screenshot below displays the page or activity to enter your value, to get the answer for the area of a circle according to the respective parameter which is the radius of the circle (r).

Now, enter the value appropriately and accordingly for the parameter as required by the **example** above where the **radius of the circle** is** 6**.

Finally, click on **Calculate**

As you can see from the screenshot above, **Nickzom Calculator** – The Calculator Encyclopedia solves for the area of a circle and presents the formula, workings and steps too.