*x*‐axis. The other is vertical and is called the

*y*‐axis. The point of intersection of the two number lines is called the origin and is represented by the coordinates (0,0).

Each point on a plane is located by a unique ordered pair of numbers called coordinates. Some coordinates are noted in Figure 2.

Notice that on the *x*‐axis, numbers to the right of 0 are positive and to the left of 0 are negative. On the *y*‐axis, numbers above 0 are positive and below 0 are negative. Also note that the first number in the ordered pair is called the *x*‐coordinate, or abscissa, while the second number is the *y*‐coordinate, or ordinate. The *x*‐coordinate shows the right or left direction, and the *y*‐coordinate shows the up or down direction.

The coordinate graph is divided into four quarters called quadrants. These quadrants are labeled in Figure 3.

Notice that

- In quadrant I,
*x*is always positive and*y*is always positive.

- In quadrant II,
*x*is always negative and*y*is always positive.

- In quadrant III,
*x*and y are both always negative.

- In quadrant IV,
*x*is always positive and*y*is always negative.

##### Example 1

Identify the points ( *A, B, C, D, E*, and *F*) on the coordinate graph shown in Figure 4.