Cartesian coordinate system
A Cartesian coordinate system, also known as rectangular coordinate system, can be used to plot points and graph lines.
The following is an example of rectangular coordinate system
It is basically, a set of two number lines
The horizontal line is called x-axis and the vertical line is called y-axis
A good real life example of a vertical number line or y-axis is a thermometer.
Notice that it has 4 quadrants.
In quadrant I, x and y are positive
In quadrant II, x is negative, but y is positive
In quadrant III, x and y are negative
In quadrant IV, x is positive, but y is negative
The center, or intersection of the two axis is equal to (0,0)
In this lesson, you will learn to plot points on the cartesian coordinate system.
A point is represented by a pair of numbers (x, y)
x stands for any value on the x-axis and y stands for any value on the y-axis
An example of a point is (1, 5)
Let us now plot some points.
Locate point (2,3).
x = 2 and y = 3
Draw a vertical line at x = 2 and draw a horizontal line at y = 3
Where the two lines meet or intersect, is your point (in red)
Locate point (-3, 1)
Draw a vertical line at x = -3 and draw a horizontal line at y = 1
The intersection of the two lines is your point
Locate point (-4, -4)
Draw a vertical line at x = -4 and draw a horizontal line at y = -4
Tricky cases are when points are located on the x-axis or the y-axis.
Students usually get confused, so study the following two examples carefully
Locate point (2,0)
Draw a vertical line at x = 2 and draw a horizontal line at y = 0.
Notice that when y = 0, your horizontal line is on the x-axis
Important point to remember:
When y = 0, your point is always located on the x-axis
Locate point (0, -3)
Draw a vertical line at x = 0 and draw a horizontal line at y = -3.
Notice that when x = 0, your vertical line is on the x-axis
Important point to remember:
When x = 0, your point is always located on the y-axis
Other examples: