Do you know what irrigation is? **Irrigation** is a method of bringing water to a large area, usually to water crops. Sometimes this is as simple as a sprinkler system above the ground. Large circles of land can be watered effectively using a more complex system called center-pivot irrigation.

#### News You Can Use

A **center-pivot irrigation** system, like the one pictured above, consists of sprinklers set up on pipes that are supported by wheeled towers. When the irrigation system moves, it travels in a circular path. In fact, it moves along the circumference of a circle. The irrigation system forms the radius of the circle, and the watering happens within the area of that circular space.

If you look closely at the picture above, you can see the water line of each irrigation system moving along the circumference of a circle. If you know the circumference of a circle, you can figure out its radius. Therefore, knowing the circumference of the area of land that needs to be watered would allow a farmer to choose an irrigation system of the correct length. Based on the circumference, he can choose a system with the best length (radius) for the area!

See for yourself: http://www.youtube.com/watch?v=X0zyqjU9Jlc

#### Explore More

The circumference of the area of land reached by a center-pivot irrigation system is 10,048 feet. Can you figure out the length of the irrigation system?