The Cartesian Plane

A Cartesian plane contains two lines, one horizontal i.e. (left to right) and the other vertical (top to bottom) intersecting at a point called the origin (0).  

The horizontal line is called the x-axis (abscissa) and the vertical line is called the y-axis (ordinate).   

e.g. \( \scriptsize \left( \underset{x\:coordinate}{2} \; \;\: \underset{comma}{,} \;\;\: \underset{y-coordinate}{5} \right) \)

The plane x, y is called the Cartesian coordinate system P (x, y)

The x-coordinate is always written first followed by a comma and then the y-coordinate 

Let’s consider the image above:

In A x = 1  , y = 5 (1, 5) 
B x = 2  , y = 3 (2, 3)
P x = 5  , y = 5 (5, 5) 

The coordinates of the origin O are (0, 0) where x = 0, y = 0 

Example 11.2.1:

What are the coordinates of the points A, B, C and D in the Cartesian plane below? 

Solution

A (2, 3) 

B (1, -2) 

C (-3, -1) 

D (-2, 4)