1. IES ”MARÍA BELLIDO”
What is the Cartesian Plane?
The Cartesian Plane (or coordinate plane) is made up of two directed real lines that
perpendicularly intersection at their respective zero points.
The horizontal axis is called the x-axis. The real numbers on the x-axis increase as you
move to the right. With respect to the vertical axis, the positive numbers are to the right
of the vertical axis and the negative numbers are to the left of the vertical axis.

2. The vertical axis is called the y-axis. The real numbers on the y-axis increase as you move
upward. With respect to the horizontal axis, the positive number to above the horizontal
axis and the negative numbers are below the horizontal axis.
What is the origin?
The point where the horizontal axis and the vertical axis intersect is called the origin.

3. All points on the plane can be located by indicating where the point is horizontally
(x-coordinate) and where the point is vertically (y-coordinate).

4. This location is written in a shorthand of an ordered pair where
• The first part of the ordered pair is the horizontal position of the point
and

5. • the second part of the ordered pair is where the vertical position of the
point.
What are quadrants?
The two axes break the Cartesian (o coordinate) Plane into four parts. These parts are
called quadrants. The quadrants are numbered I, II, III, and IV started with the top
right quadrant and working counter clockwise.

6. • The points in quadrant I have x-coordinates and y-coordinates which are both
positive.
• The points in quadrant II have x-coordinates which are negative and y-
coordinates which are positive.
• The points in quadrant III have x-coordinates and y-coordinates which are
both negative.
• The points in quadrant IV have x-coordinates which are positive and y-
coordinates which are negative.
It is assumed that you already know how to graph points in the plane. This is intended to
be a quick review of the Cartesian Plane . There are several sources on-line with additional
information about the Cartesian Plane.