How to Calculate the Area of a Circle
In this video we will learn how to calculate the area of a circle and how to find the area of a ring. Doubleclick the play button to start the video.
If you want to quickly find the area of a circle, use this
free online geometry calculator.
Definitions
The distance around a circle is called the circumference.
The surface inside a circle is called the area of the circle.
A segment connecting the center of a circle with any point from the circle is called radius.
A segment that passes through the center of a circle and connects two opposite points from the circle is called diameter.
The radius is half the diameter.
Example
The radius of a large pizza is 20 inches. Find its area and round the answer to the nearest whole number.
First, we have to find the radius of the pizza.
r = d/2 = 20/2 = 10 in
Area = 3.14 x 10^2 = 3.14 x 100 = 314 square inches
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