Graphing On A Coordinate Plane

Plotting Points

On a number line, each point is the graph of a number. On a plane, each point is the graph of an ordered pair. The coordinate plane is formed by the intersection of the horizontal axis, denoted the x-axis, and the vertical axis, denoted the y-axis. These axes are called coordinate axes.

The numbers in the ordered pair are called coordinates, with the first coordinate indicating the direction on the x-axis and the second coordinate indicating the direction on the y-axis. If one of the coordinates is zero, then the point is on of the axes.
In the ordered pair (3,4), the first number, 3, is the x-coordinate and the second number, 4, is the y-coordinate. Observe the ordered pair (4, 3). Now the first number, 4, is the x-coordinate and the second number, 3, is the y-coordinate.
 



 


Try Exercise #1

Plot the points (-3, 4), (2 ,-5), and (-4, -4) on your sheet of graph paper. Write the ordered pair next to each point.
CHECK YOUR ANSWERS HERE!!!!!

When one coordinate is 0, the point is one of the axes. The origin, the point where the x-axis and the y-axis intersect, has coordinates (0, 0)

Try Exercise #2

Plot the following points on your coordinate plane. (-2, 0) and (0, -3).
CHECK YOUR ANSWERS!!!!!

Get some more practice on the maze game.

Quadrants

The coordinate plane is divided into 4 regions, called quadrants, which are denoted by Roman numerals. The point (2, 4) is located in the first quadrant. The point (-3, 2) is located in the second quadrant. The point (3, -4) is located in the fourth quadrant.


 


What can you conclude about the types of coordinates that must fall into the quadrants? A point may fall in a quadrant or on an axis. The axes are not part of any quadrant since it is on the boundary between quadrants. The following diagram illustrates the signs of the coordinates in each quadrant.
 



 


Try Exercise #3

In what quadrant is each point located?

A(-6, -4), B(-13, 4), C(10, -14), and D(3, 4).
Check Your Answers Here!!!!!

Finding Coordinates

We can identify the coordinates of a point by counting the number of units a point is to the right or left of the y-axis and the number of units up or down from the x-axis.
 



 


Point A on the graph is 4 units to the right and 3 units up. It's coordinates are (4, 3).

Try Exercise #4

Find the coordinates of B, C, D, E, F, and G.
Check Your Answers Here!!!!!
 

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