Introduction
Equation of a Circle

A teenager, the moon, and a glowing circle

You can write an equation of a circle in a coordinate plane if you know its radius and the coordinates of its center. In this topic, you will solve problems involving circles and the coordinate plane. In order to solve these problems, you will learn the following information:

Essential Questions

 

Warm-Up

A grid

Warm-up iconYou have been getting horrible reception on your cell phone for the past two weeks. Your cell phone company has agreed to give you a “mini tower,” which you must install at home. As long as the cell phone is within close proximity of the “mini tower,” your reception will receive a boost. The grid shown represents the location of your home and the locations that you frequent. Keeping in mind that you must install the “mini tower” at home, will your cell phone receive a boost at each location?

Hover your cursor over the grid to view the range of the "mini tower." The range of the “mini tower” is represented by the area within the circle. You can see that the “mini tower” will fall short in a few locations.

Although you will receive a boost while at school and the gym, you will still have horrible reception while at church, the grocery store, and at work. Sadly, the "mini tower" will not be enough to fix your reception problem. Cell phone companies follow these steps when deciding on the placement of cell phone towers.  The companies must guarantee that their towers can cover a range that will satisfy their customers.