### Area of a Rectangle

#### Lesson Objective

In this lesson, we will learn about the area of a rectangle.

#### About This Lesson

In this lesson, we will:

- Learn about the formula to find the area of a rectangle.
- See an example on using the formula to calculate a rectangle's area.
- See another example on using the formula to calculate the width of a rectangle.

The study tips and math video below will explain more.

### Study Tips

#### Tip #1

A rectangle has four right angles. The sides of a rectangle that are opposite each other have the same length.

Note that, the longer side of a rectangle is the length and the shorter side is the width. Also, a square is a special type of rectangle.

Now, for a rectangle with length l and width w, its area, A will be:

The math video below will give more explanation on this. Also, we will see some examples on how to use this formula.

### Math Video

#### Math Video Transcript

00:00:03.150

In this lesson, we will learn about the area of a rectangle.

00:00:08.22

Consider this rectangle with the length of L, and the width of W.

00:00:14.080

Now, we can get the area of the rectangle, by multiplying its length L with its width W.

00:00:21.150

With this, we get the area, A equals to, L multiply W. This gives LW.

00:00:30.190

Note that, it is very important to include the unit. Since we are multiplying L with W, the unit for the area will be in the form of square unit.

00:00:41.240

We will see more explanations on this in the upcoming example.

00:00:46.170

Now, let's see some examples on using this formula.

00:00:51.090

Find the area of this rectangle when its length is 4cm, and its width is 3cm.

00:00:58.160

To solve this, we start with the formula for the area of a rectangle, A equals to LW.

00:01:06.150

Since the length is given as 4cm, we can substitute L with 4.

00:01:13.020

Similarly, since the width is given as 3cm, we can substitute w with 3.

00:01:20.120

Next, we can simplify by multiplying 4 with 3. This gives 12.

00:01:27.220

Now, this number is meaningless unless we include the unit for it.

00:01:32.220

Since the length and width are given in centimeter, the unit for the area will be in square centimeter.

00:01:39.230

Hence, the area of this rectangle is 12 square centimeter.

00:01:47.010

Next example, given that the area of this rectangle is 20 square feet, and its length is 5ft. Find its width.

00:01:56.100

Again, we start with the formula for the area of a rectangle, A equals to LW.

00:02:03.060

Since the value of the area and the length is given, we can find the width, by solving this equation for w.

00:02:10.110

Here’s how. Since the area is given as 20 square feet, we can substitute A with 20.

00:02:17.140

Similarly, since the length is given as 5ft, we can substitute l with 5.

00:02:24.060

Now we have, 5w equals to 20.

00:02:28.160

Let's rewrite this equation so that it will look neater.

00:02:32.230

To find W, we need to remove 5. To do so, we divide both sides of the equation with 5.

00:02:42.060

After doing so, we have, W equals to 20 over 5.

00:02:48.080

20 divide by 5 gives 4.

00:02:51.180

Now, this number is meaningless unless we include the unit for it.

00:02:56.160

Since the length is given in feet, the width of the rectangle will also be in feet.

00:03:02.040

Therefore, the width of this rectangle is 4 ft.

00:03:07.110

That is all for this lesson. Try out the practice question to further your understanding.

### Practice Questions & More

#### Multiple Choice Questions (MCQ)

Now, let's try some MCQ questions to understand this lesson better.

You can start by going through the series of questions on the area of a rectangle or pick your choice of question below.

- Question 1 on finding the area of a rectangle
- Question 2 on finding the width of a rectangle

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