A coordinate plane is formed by two number lines that intersect at right angles. The point of intersection is the ZERO on each number line – it is called the origin.

The two number lines are called the axes.
The horizontal axis is called the x-axis.
The vertical axis is called the y-axis.

The two axes divide the coordinate plane into four quadrants.

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To give the location of a point on a coordinate plane, you need to use TWO numbers, called an “ordered pair”. The first number tells how far to move right (positive) or left (negative) from the origin. The second number tells how far to move up (positive) or down (negative) from the x-axis.

The numbers in an ordered pair are called coordinates. The first number is called the x-coordinate and the second number is called the y-coordinate. The coordinates for the origin in (0, 0).

Drag Point A around the plane. Notice as the coordinates change. Also notice the quadrant you are in.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now) Duane Habecker, 03/14/2010, Created with GeoGebra