What Are Cartesian Coordinates?
What Are Cartesian Coordinates?
Cartesian coordinates are used to describe the position of a point on a graph.
The image below shows a graph. A point is plotted on the graph (a blue cross) with its Cartesian coordinates written beside it: (2, 4).
Don't forget: a graph has a pair of axes: the horizontal axis is called the xaxis and the vertical axis is called the yaxis. They meet at the origin. We can plot points, lines and curves on a graph.
Interactive Widget
Use this interactive widget to generate Cartesian and polar coordinates. Simply click in the shaded area.
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Turn your phone on its side to use this widget.
How Do Cartesian Coordinates Work?
Cartesian coordinates work by measuring how far the point is from the origin.

First you measure how far across the point is (in the horizontal direction) by measuring how far along the xaxis it is. This is called the xcoordinate.
The point above is 2 units along the xaxis so its xcoordinate is 2.
Note: The xaxis is labelled with numbers (0, 1, 2, 3...) so you can measure how far across the point is.

Then you measure how far up the point is (in the vertical direction) by measuring how far up the yaxis it is. This is called the ycoordinate.
The point above is 4 units along the yaxis so its y coordinate is 4.
Note: The yaxis is labelled with numbers (0, 1, 2, 3...) so you can measure how far up the point is.

The xcoordinate (2) and the ycoordinate (4) are then written in brackets, separated by a comma. The xcoordinate is on the left, the ycoordinate is on the right.
Cartesian Coordinates in General
In general, we write Cartesian coordinates as:
x is the xcoordinate.
y is the ycoordinate.
x and y can taken any number (whole or fraction, positive or negative).