Circle Area

What is a Circle?

It is a geometric figure achieved by drawing a curved line that is always equidistant from a central point. The distance from this central point to the curved line is called the radius.

How to Find the Area of a Circle

The area of a circle represents the number of surface units inside a circumference. To calculate the area, you must first know the length of its radius (r), which is the distance from the center point of the circle to its outer circumference. Another way to obtain the radius of a circle is to divide the length of its diameter (d) by 2.

Formula to calculate the area of a circle:

Circle Area = π · radius²

Practical Example

Let's say we need to find the area of a circle, and we are given the length of its diameter, which for this example, we'll assign a value of 8 [cm].

Step 1: Determine the radius length (r)

If we already know the diameter (d) of the circle, then by dividing it by 2, we obtain the radius (r). For this example, then:

Radius = diameter ÷ 2
Radius = 8 ÷ 2
Radius = 4 [cm]

If the exercise statement provides you with the radius directly, you can skip this step and proceed directly to step 2.

Step 2: Replace the obtained radius in the area formula

From the previous step, we obtained the value of the radius = 4 [cm]. What remains is to replace this length in the formula to calculate the area of the circle.

Circle Area = π · (4)²
Circle Area = π · 16
Circle Area = 50.26 [cm²]

And that's it. We have calculated the area or surface of a circle quickly and easily. It is important to remember the relationship between the diameter and the radius to be able to solve any mathematical exercise of this kind.