Plotting Points In The Plane


When plotting, remember that the first number is for the horizontal axis and the second number is for the vertical axis.

Example: Plot the point (4, –5).

1. Start at the origin

2. Count four units on the X axis as the first number represents the x asis

3. Count five units on the Yaxis as the second number in the bracket denotes the number to be plotted on the Y axis

4. Dot the point in the intersection

A coordinate system is a two-dimensional number line. 

For Example: two perpendicular number lines or axes.

This is a typical coordinate system:

The horizontal axis is called the x-axis and the vertical axis is called the y-axis

The center of the coordinate system (where the lines intersect) is called the origin. The axes intersect when both x and y are zero. The coordinates of the origin are (0, 0).

An ordered pair contains the coordinates of one point in the coordinate system. A point is named by its ordered pair of the form of (x, y). The first number corresponds to the x-coordinate and the second to the y-coordinate.

Shown below is the demonstration on how to plot a point

1. The ordered pair (3, 4) is found in the coordinate system when you move 3 steps to the right on the x-axis and 4 steps upwards on the y-axis.

2. The ordered pair (-7, 1) is found in the coordinate system when you move 7 steps to the left on the x-axis and 1 step upwards on the y-axis.

To find out the coordinates of a point in the coordinate system you do the opposite. Begin at the point and follow a vertical line either up or down to the x-axis. There is your x-coordinate. And then do the same but following a horizontal line to find the y-coordinate.