Objectives:
- Define vocabulary associated with the coordinate plane (ordered pair, origin, quadrant, x-axis, y-axis, x-coordinate, and y-coordinate)
- Identify the quadrant that a point lies in
- Plot points on the coordinate plane
- Determine the ordered pair of a point in the coordinate plane
What is a coordinate plane?
A coordinate plane is a two-dimensional number line. The horizontal line is the x-axis and the vertical line is the y-axis. The origin is the point where the x-axis and y-axis intersect. This point is (0,0).
A coordinate plane is a two-dimensional number line. The horizontal line is the x-axis and the vertical line is the y-axis. The origin is the point where the x-axis and y-axis intersect. This point is (0,0).
The coordinate plane is broken up into 4 quadrants: Quadrant I, Quadrant II, Quadrant III, and Quadrant IV.
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A point that lies in Quadrant I will have both a positive x-coordinate and y-coordinate.
A point that lies in Quadrant II will have a negative x-coordinate and a positive y-coordinate. A point that lies in Quadrant III will have both a negative x-coordinate and y-coordinate. A point that lies in Quadrant IV will have a positive x-coordinate and a negative y-coordinate. |
We also need to think about a point that falls on the x-axis or y-axis. Which quadrant would these points lie in? The answer is that these points DO NOT lie in any quadrant.
Determining the Quadrant a Point Lies In
We can write a point as an ordered pair. An ordered pair is written as (x,y) where the x-coordinate is written first then the y-coordinate is written second. For example, if we had an x-coordinate of 2 and a y-coordinate of 4 then the ordered pair would be written as (2,4). This point lies in Quadrant I since both the x- and y-coordinates are positive. Let's look at some more examples below!
Example #1
Your turn! Given the points below, determine which quadrant each point lies in:
Click HERE to check your answer.
Plotting Points in the Coordinate Plane
We plot points on the coordinate plane by "running" then "rising".
As stated earlier, we always start with the x-coordinate since the points are written as (x,y). The x-coordinate tells us how much to "run" left or right. The y-coordinate tells us how much to "rise" up or down.
Let's look at an example below:
Example #2
Your turn! Plot the following points in a coordinate plane:
Click HERE to check your answer.
How to Write an Ordered Pair Given a Graph
In order to write an ordered pair, we will always need to start from the origin. Remember that the origin is at (0,0). Hence, we will start at (0,0) and look to see how much a point is to the left or right from the origin. This will be our x-coordinate. Next, we will look at how much the point is up or down from the origin. This will be our y-coordinate. We will write our answer as (x,y) with the x-coordinate first and the y-coordinate second.
Example #3
Your turn! Given the points on the graph below, write the ordered pair for each point:
Click HERE to check your answer.
Quiz
You will take the quiz after you have researched and taken notes.
CLICK HERE FOR QUIZ
CLICK HERE FOR QUIZ