Let’s take a look at graphing points on a co-ordinate plane. The first thing we’ll need are two intersecting lines, but not just any intersecting lines, we need perpendicular lines. These lines intersect at a ninety-degree angle, so they’re
perpendicular and they’re the start of our coordinate plane.
Before we say anything else about our coordinate plane, we need to know a few
new words. The point where these two lines intersect, the point where they cross, is
called the origin. The line that runs left and right is called the 𝑥-axis. The line that runs up and down is called the 𝑦-axis.
If you look closely on this co-ordinate plane, you’ll also see some numbers. The 𝑥- and 𝑦-axis are kind of like number lines. If we’re looking at the 𝑥-axis and counting one,
two, three, what number should be at the origin? Well the origin
should be zero. And if we’re looking at the 𝑦-axis as a number line, what should
be at the origin? Also zero.
So when we write the origin, we write it like this: zero, zero. The reason we write like this is because the coordinates are zero for the
𝑥-axis and zero for the 𝑦-axis. The name of this video though is graphing points on a coordinate plane, so
let’s get started with graphing. But the point of this video is graphing things on a coordinate plane, so
let’s get started with that.
The most important thing to remember is that when we’re graphing things on a
coordinate plane, we start with the 𝑥-axis and then we move to the 𝑦-axis The format looks like this: we start with the 𝑥-coordinate, and then we have the
𝑦-coordinate; and these are given in numbers, so we have an open parentheses, the
𝑥-coordinate comma the 𝑦-coordinate, close parentheses.
In other words, the first number, our 𝑥-coordinate tells us how
far left or right and our second coordinate, our 𝑦-coordinate tells us how far to
go up or down. Again, in order to graph things on a coordinate plane, we need two numbers: an 𝑥-value and a 𝑦-value. And 𝑥 always comes first, just like in the alphabet.
You might be given the coordinate one, three. What would it look
like to graph one, three?
Well because we have our 𝑥 and then our 𝑦,
we need to go to the right one and up three; and our point is located there.
So now I want you to try. Use the coordinate plane to find the coordinates of
the origin and point C. By looking at the coordinate plane, you should be able to find the location of the origin and point C.
First off, for the origin, the origin is always located at zero, zero;
and it is located at zero, zero on this graph. Point C is located at two, one.
It’s two to the right and one unit up.
Sometimes we use coordinate planes to help us read maps. Look closely at the map and see if you can find the coordinates of the Ferris
wheel, the ice cream truck, and the train. Remember, the format is the 𝑥-coordinate, how far left and right,
and then the 𝑦-coordinate, how far up and down.
The Ferris wheel is located six units to the right and six units up. The ice cream truck is one unit to the right and two units up. And finally, the train is located six units right and two units up. I know what you’re thinking. Okay, so coordinate planes are good for maps, but
who else really uses them?
Here’s an example, one person that might use coordinate planes is a city
planner or an architect. They design streets, and they tell us where are the best places to put
houses, and they use coordinate plane systems to do that. Pilots use co-ordinate planes in their navigational systems. They use
coordinate planes to get us from point A to point B, from one city to the next. Another really cool job that might use a coordinate plane is marine
biologist. A marine biologist might use a coordinate plane to map out a shipwreck. They have to
be really accurate when they describe where they found certain artifacts.
Now that we’ve talked about how to use a coordinate plane and who might use
a coordinate plane, I want to remind you of the vocabulary words we talked about today. Coordinate planes consist of an 𝑥-axis and a 𝑦-axis. These two lines intersect at the origin, and we always write coordinates with the
𝑥 first and the 𝑦 second. If you remember these words and don’t forget to put the 𝑥 first
and the 𝑦 second, you’ll be on your way to graphing points in a coordinate plane.