The Cartesian Coordinate System, named after Rene Decartes, is used to find precise locations in a 2D space. Using the same coordinates, you are able to draw various shapes and lines and find the relationships between them. In our 2D space, a single location is made up of two points, X and Y.
The X coordinate is always horizontal (left and right) and Y coordinate is always vertical (up and down). These points are placed on a graph that contains four distinct quadrants.
This may start to sound confusing, so let's take a look at the graph itself:
To locate a point on the graph, simply go to the orgin (the point where x=0 and y=0). If your X coordinate is negative, count to the left (negative numbers, just like the number line), otherwise count to the right to the value of X. Next, if your Y value is negative, go down from where your X value was; if your Y value is positive, go up from where your Y value was. Once you go up or down enough spaces to be the same as your Y value, you have your point! Draw a little dot on your graph and label it, and you have precisely defined a point!
Note: To label your point, simply write the X and Y value next to the dot you draw inside of parenthesis. For example, if your X was 3 and your Y was -4, next to your dot, you would write (3,-4). Remember, the X coordinate is always written before the Y coordinate when you are dealing with points!
That's really all there is to the basics of working with points in the Cartesian Coordinate Systems. Using the same system, however, you'll be using the Slope-Intercept formula to draw and compare lines and line segments. Read about the Slope Intercept formula now!
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