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Write four JavaScript functions to calculate areas and volumes.

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[MUSIC]
0:00

This practice session covers
basic JavaScript functions.
0:04

It's a great followup to the fifth
part of the JavaScript Basics course.
0:07

If you haven't taken that yet, and
find this practice session too difficult,
0:11

then go through the first five
parts of that course first.
0:15

I've added a link in
the teacher's notes below.
0:18

For this practice session,
you'll write four functions.
0:20

Call those functions and
output the results to the console.
0:23

It's pretty simple but
combines the basics of creating and
0:27

using JavaScript functions.
0:30

I've attached a workspace to this video
which includes some starter files and
0:31

instructions.
0:35

Open up the workspace and
open up the geometry.js file.
0:36

You'll see six instructions
listed as JavaScript comments.
0:39

Here's what you should do.
0:43

First attach the JavaScript
file to the index.html file.
0:45

After all, the program won't work at
all unless the web page loads it.
0:48

Next create a function that
calculates the area of a rectangle.
0:52

To calculate the area of a rectangle,
you multiply the width by the height.
0:56

So this function needs
to accept two arguments,
1:01

do some math,
then return the results back.
1:04

Then you'll create another
function to calculate the volume
1:06

of a rectangular prism.
1:09

Also known as a box.
1:11

For that, you multiply the width
by the height by the length.
1:13

This function should return the volume.
1:16

Now the next two functions involve
calculating the area of a circle and
1:19

the volume of a sphere.
1:23

These both require using the JavaScript
math object to get the value of pi.
1:24

And to use a method that lets you
raise the number to a certain power.
1:29

For example x to the second power or
x squared.
1:33

Now I didn't cover those in
JavaScript basics course, so
1:37

you'll need to do a bit of research
to figure out how to use them.
1:40

I've included links in
the teacher's notes below.
1:43

Okay so if you have the radius of a circle
to calculate the area of a circle,
1:46

you take pi times the radius squared.
1:51

Squared is also refered as the second
power or to the second power.
1:54

So the function will receive
a radius value and return the area.
1:58

The last function will calculate
the volume of a sphere.
2:02

To do that you multiply four thirds by pi,
by the radius cubed or
2:05

the radius to the third power.
2:09

Okay now finally you'll
add four lines to log out
2:11

the results of your function
to the JavaScript console.
2:15

It's not super exciting to look at, but
this is what your output should look like,
2:19

something like this.
2:23

Now if you wanna do some quick study
before tackling this practice session.
2:24

In the teacher's notes look for
2:27

links to videos that can help
you solve this challenge.
2:29

But if you're ready, go for it.
2:31

Program your solution and I'll show
you my solution in the next video.
2:33

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