Math: the Cartesian Plane
Tutoring math, you know that everyone needs to learn this. The math tutor provides an introduction.
Most people are familiar with the idea of a two dimensional grid. You can indicate specific locations (points) on the grid by saying how far across to go, then how far up or down.
In grade school math, the starting place is the centre of the plane, where the two axes (lines) cross. That central point is called the origin. The location of every other point is described relative to the origin. The line going across is the x axis; the one going up and down is the y axis. If all the grid lines are showing, the x and y axes will be labeled.
The coordinates of a point are the numbers that tell its location. They are written in brackets, with the x coordinate first. Since the x axis runs across, the first coordinate tells how far across to go (from the origin), while the second coordinate tells how far up or down to go. Of course, the coordinates of the origin are (0,0).
Therefore, every point can be thought of as
(across, up or down)
and also as
(x,y)
If the across number is negative, you go left. If it’s positive, you go right. If the “up or down” number is positive, you go up. If it’s negative, you go down.
One last hint: the numbers mean “moves”. To go to (5,-3), for instance, you start at the origin, move five squares right, and then three down. Behold:
That’s your introduction to the Cartesian plane.
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.
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