Video Transcript
Let’s take a look at graphing
points on a coordinate 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
coordinate 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 coordinate 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.
