CHAPTER

11

Graphing

The Rectangular Coordinate Plane

In Chapter 9 some concepts of geometry were explained. This chapter

explains the concepts of combining algebra and geometry using the

rectangular coordinate plane.

The rectangular coordinate plane uses two perpendicular number lines

calledaxes. The horizontal axis is called thex axis. The vertical axis is called

they axis. The intersection of the axes is called theorigin. The axes divide the

plane into fourquadrants, called I, II, III, and IV (see Fig. 11-1).

Plotting Points

Each point on the plane can be located by itscoordinates. The coordinates

give the horizontal and vertical distances from the y axis and x axis, respec-

tively. The distances are called thex coordinate (abscissa)and they coordinate

(ordinate), and they are written as anordered pair(x, y). For example, a point

with coordinates (2, 3) is located two units to the right of the y axis and 3

units above the x axis (see Fig. 11-2).

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