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title: Surface Area of a Sphere
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## Surface Area of a Sphere

The surface area **A** of a sphere with radius **r** may be calculated by the following formula:
#### A = 4πr²
where **&pi;** is the ratio of a circle's circumference to its diameter (<em>&pi;</em> &approx; 3.14159).

### Example:
*Problem:* Given a sphere with a radius of 11 inches, find its surface area.

*Solution:* A = 4&times;*&pi;*&times;11&sup2; &approx; 1520.5 square inches

#### More Information:

- [Wikipedia](https://en.wikipedia.org/wiki/Sphere)