Mathematicians use a system of intersecting number lines to
help locate points. Using these intersecting numbers lines, they creates a
coordinate system.
A coordinate system is formed by the intersection of a
horizontal number lines, x-axis, and a vertical line, the y- axis.
The lines intersect at the origin, (0,0) Any points can be
described by using an ordered pair(x,y)
The first coordinate, x, of an ordered pair tell you how
far you move to the left or to the right from the origin along the x-axis.
the second coordinates, y, on an ordered pair the y-
coordinate tell you how far you move down or up from the x-axis.
the x-axis and the y- axis divide the coordinates grid into
four quadrant.
Example 1
Plot the points (-4,3) and (4,-3)
To plot the point(-4,3), start at the origin. Move 4 spaces to the left on the
x-axis and 3 spaces down from x-axis.
To plot the point (4,-30 start at the origin. Move 4 spaces to the rigth on the
x-axis and 3 spaces down from x-axis.
Practice
Plot each point on a coordinate grid,
A.(-1,-2) B.(-5,0) C. (2,-3) D. (-3,-2)
Example 2
High and low tides are usually related to sea level. The points on the graph
show the low and high tides, to the nearest foot, for several days. The
x-coordinate represents low tide and the y-coordinate represents high tide. What
are the coordinates of point E? Describe the low and high tides on that day.
To move from the origin, first move left 1 unit. Because we moved left, the
x-coordinate is -1.
Then move up 2 units. Because we moved up, the y-coordinates is 2.
The is(-1,2). The low tide was -1 foot(1 foot below sea level), and the high
tide was 2 feet above sea level.
Practice
1. To plot the point (-2,-4);
a. The -2 tells you to move 2 spaces along the ________ axis.
b. Should you move right or left? Why?
c. The -4 tells you to move 4 spaces from the ________ axis.
d. Should you move up or down? Why?
2. Plot each point on coordinates grid.
i. (5,-2) ii. (-5,0) iii.(-1,-2.5) iv(3.5,-2.5)
3. Find the coordinates of each point.
i. A ii. B iii. C iv. D v. E vii. F
4. Name the points for each ordered pair.
a. (4,6) b. (6,-3) c. (0,-4) d. (-5, 5)
When you use a pair of coordinate you can create an art
theme. see the following example:
Another one
