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# What Is the Formula for the Area of a Circle?

The formula for the area of a circle is pi multiplied by the radius of the circle squared. The radius of the circle is the length of a straight line stretching from the center of the circle to the line of circumference. It is equal to half the diameter.

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The approximate value of pi is 3.14. Pi is the ratio of a circle's circumference to the circle's diameter. If a circle has a radius of 5 inches, the area of that circle equals 3.14 x 5^2, or 78.5 square inches. The circumference is equal to pi times the circle's diameter. If the same circle is used, the diameter is equal to 10 (two times the radius), so the circumference equals 3.14 x 10, or 31.4 inches.

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Q:
## Why Is Pi Important?

A: If the circumference or the area of a circle is known, pi can be used to find the diameter and the radius of that circle. Likewise, if the radius or diamet... Full Answer >Filed Under: -
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## What Is the Formula for Finding the Volume of a Cylinder?

A: The formula for finding a cylinder is to multiply its base (B) and height (h) together, where the area of the base is given as pi multiplied by the radius ... Full Answer >Filed Under: -
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## How Do You Find the Volume of a Cylinder?

A: The formula for the volume of a cylinder is derived from the area of a circle. By finding the area of the base of the cylinder, you can multiply it by the ... Full Answer >Filed Under: -
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## How Do I Calculate the Apothem of a Triangle?

A: An apothem of a triangle depends upon either the length of one of its side or the radius of a circle that fits inside it. There are two methods of determin... Full Answer >Filed Under: