In Chapter 2 you learned how to represent numbers, operations, and other ideas with letters and symbols.
In this chapter, we add a special kind of drawing to your mathematical tool kit. You'll see how something called a coordinate system combines algebra with the picture power of geometry. You probably have seen coordinate systems before, even if you never studied them in school.
In fact, you use one every time you read a map. We'll start there and gradually sharpen the simple, basic idea into a powerful mathematical tool.

On the U.S. map in Display 3.1, Denver, Colorado, is in 4C and Atlanta, Georgia, is in 8D.

1. Where is Portland, Oregon?

2. Where is Washington, DC?

3. What city is in 6B?

4. Describe how this code works. What do the numbers represent? What do the letters represent?

Learning Outcomes
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After studying this section, you will be able to:

Construct rectangular coordinate systems for the plane using various points of origin and unit lengths;

Name points in the plane by using coordinate axes;

Mark the locations of ordered pairs in the coordinate plane.