Cartesian plane

In this lesson we will remember some basic concepts that we will have to dominate when working with functions. Read the video transcription and then whatch the video as many times as you need. Then, get some practice with the exercise button.

VIDEO TRANSCRIPTION

In this video we will learn about the coordinate plane and some important elements in this plane. The two perpendicular lines are called axis. The horizontal line is the x-axis and the vertical line is the y-axis. These two axes divide the plane in four important regions. We will talk about them later.

The intersection point between these two lines is the origin or 0. The positive numbers are located to the right of the origin on the x-axis, and the negative numbers are to the left of 0. 

When graphing integers on the number line remember to keep the same distance between two consecutive integers, also on the y-axis. 

The positive numbers are located above zero and the negative numbers are located below the origin.

The upper right area of the coordinate plane is called the first quadrant or quadrant one. 

The upper left area is quadrant two. 

The bottom left part of the coordinate plane is called quadrant three and the last quadrant is quadrant four. 

Any point in the coordinate plane is characterized by two coordinates. Let’s consider point. A point a is located in quadrant one. To find its coordinates simply draw two parallel lines to the two axes and read the two numbers at the intersection. The first number located on the x-axis is 3 and the number located on the y-axis is 2. 

The first number is the x-coordinate and the second number is the y-coordinate of point A. The order is very important so A has coordinates three and two.

Let’s read the coordinates of point B. The first one is negative four. That is the x-coordinate and the second one is three positive, which is the y-coordinate of point B.

Let’s take a point in quadrant three. Remember to draw parallel lines to the two axes and read the points of intersections. The first number is negative 2. Always read first the number that is located on the x-axis and then the number that's on the y-axis.