Plotting a Point
If the xcoordinate and the ycoordinate of a point are given, we can plot
the point on a Cartesian coordinate system.
Procedure â€”
To Plot a Point on a Cartesian Coordinate System
Step 1 Draw (or imagine) a vertical line through the xcoordinate of
the point.
Step 2 Draw (or imagine) a horizontal line through the ycoordinate
of the point.
Step 3 Place a dot where the lines intersect.
Example 1
Plot the point (3, 7) on a Cartesian coordinate system.
Solution
Step 1 Draw (or imagine) a vertical line through the xcoordinate of the
point.
Draw a vertical line through the xaxis at 3.
Step 2 Draw (or imagine) a horizontal line through the ycoordinate of
the point.
Draw a horizontal line through the yaxis at 7.
Step 3 Place a dot where the lines intersect.
Example 2
Plot each point on a Cartesian coordinate system.
Solution
Exercise 3
The data in the table represent the total distance traveled by a car in
0 hour, 1 hour, 2 hours, and 3 hours. Plot the data on a Cartesian
coordinate system.
t time (hours) 
d
distance (miles) 
0 
0 
1 
40 
2 
80 
3 
120 
Solution The data correspond to these points: (0, 0), (1, 40), (2, 80), (3, 120)
To plot these points, we change the way we display the coordinate system.
Horizontal axis:
â€¢ The first column in the data table represents time, so we label the
horizontal axis t instead of x.
â€¢ The times are between 0 and 3 hours, so we change the scale of the
horizontal axis so each mark represents 0.25 hours.
â€¢ There are no negative times, so we do not show much of the negative
horizontal axis.
Vertical axis:
â€¢ The second column in the data table represents distance, so we label the
vertical axis with the letter d instead of y.
â€¢ Since the distances range from 0 to 120 miles we change the scale of the
vertical axis so that each mark represents 10 miles.
â€¢ There are no negative distances, so we do not show much of the negative
vertical axis. The four points are plotted on the graph.
