How To Find The Area Of a Circle

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How To Find The Area Of a Circle

Geometry is the more fun part of math, however, it does have its ups and downs. The more notable annoyance is figuring out the area of a circle, which while simple to deal with, the fact that it relies on an approximate value makes it a lot harder to properly figure out. Nevertheless, you will have to learn how to figure it out in order to deal with problems that involve circles, so how to find the area of a circle?

Get The Diameter

A circular roundabout

The first thing that you will need is the diameter of the circle in question, and it is rather easy to figure out. The diameter of a circle (expressed with the symbol "D") is the length that runs from one side of the circle to the other through the center of the circle, and it usually is given in the parameters of the problem itself.


Find The Radius

A block of metal with a circular hole cut out

The radius (expressed with the symbol "r") is the line that goes from the edge of the circle to the center point of the circle. It is either measured directly, given in the fundamental parameters of the problem, or is calculated using the value of the diameter itself (D = r x 2). While the diameter itself does not go into the formula itself, the radius does so make sure that you are ready to calculate it.

Know The Value Of Pi

A circular hole in a fence

One thing you will need to know is the value of Pi, which is the approximation element that was mentioned earlier. Pi is a value of constance and it represents the ratio of a circle's circumference, more or less the ratio of the edge of the circle. The commonly approximated value is 3.14159, however, a vastly accepted value of this approximation is 3.14.

Calculate The Area

A set of pencils arranged in a circle

Now that we have everything that we need, we can follow the formula to get the value for the area (A) of the circle in question.

The formula is A = π x (r x r).

So a circle with a radius of 8 millimeters, will have an area of 3.14 x (8 x8) which equates to 200.96 square millimeters.

Finding the area of a circle is a pretty straightforward job, with a simple to understand the formula, however, it has a pitfall with the value of pi. As long as you remember the formula, remember the approximate value of pi, take the time to find the value of the radius and follow the formula, you will be just fine.

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