Examples with solutions for Area of a Rectangle: Finding Area based off Perimeter and Vice Versa

Exercise #1

The area of a rectangle is equal to 32.

Calculate the perimeter of the rectangle.

323232888444AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since we know that in a rectangle, each pair of opposite sides are equal to each other, we can claim that:

AC=BD=4 AC=BD=4

AB=CD=8 AB=CD=8

Now we can calculate the perimeter:

4×2=8 4\times2=8

8×2=16 8\times2=16

16+8=24 16+8=24

Answer

24

Exercise #2

The area of the rectangle below is equal to 24.

Calculate the perimeter of the rectangle.

242424666444AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Given that in a rectangle all pairs of opposite sides are equal to each other, it can be argued that:

AB=CD=6 AB=CD=6

AC=BD=4 AC=BD=4

Now calculate the perimeter of the rectangle by adding all the sides:

4+4+6+6= 4+4+6+6=

8+12=20 8+12=20

In other words, the data of the rectangle's area is unnecessary, since we already have all the data to calculate the perimeter, and we do not need to calculate the other sides.

Answer

20

Exercise #3

The area of a rectangle is equal to 8.

Calculate the perimeter of the rectangle.

888444222AAABBBDDDCCC

Video Solution

Step-by-Step Solution

According to the properties of the rectangle, all pairs of opposite sides are equal.

AB=CD=8 AB=CD=8

AC=BD=2 AC=BD=2

Now we calculate the perimeter of the rectangle by adding all the sides:

4+4+2+2=8+4=12 4+4+2+2=8+4=12

Answer

12

Exercise #4

The perimeter of the rectangle below is equal to 30.

What is the area of the rectangle?

101010555AAABBBDDDCCC

Video Solution

Step-by-Step Solution

We use the formula to calculate the area of a rectangle: length times width:

AC×AB=S AC\times AB=S

We replace the existing data:

5×10=50 5\times10=50

That is, the information that the perimeter of the rectangle is equal to 30 is unnecessary, since all the data to calculate the area already exist and it is not necessary to calculate the other sides.

Answer

50

Exercise #5

The area of the rectangle below is equal to 45.

Calculate the perimeter of the rectangle.

454545999555AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rhombus all opposite sides are parallel and equal to each other, we can claim that:

AC=DB=5 AC=DB=5

AB=CD=9 AB=CD=9

Now let's calculate the perimeter by adding all sides together:

5+9+5+9=10+18=28 5+9+5+9=10+18=28

Answer

28

Exercise #6

The area of the rectangle below is equal to 66.

Calculate the perimeter of the rectangle.

666666111111666AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=11 \text{AB=CD}=11

AC=BD=6 AC=BD=6

Now let's calculate the perimeter by adding all the sides together:

6+11+6+11=12+22=34 6+11+6+11=12+22=34

Answer

34

Exercise #7

The area of a rectangle is 21.

Work out the perimeter of the rectangle.

212121777333AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=7 AB=CD=7

AC=BD=3 AC=BD=3

Now let's add all the sides together to calculate the perimeter:

3+7+3+7=6+14=20 3+7+3+7=6+14=20

Answer

20

Exercise #8

The area of a rectangle is equal to 105.

Calculate its perimeter using the data in the figure below.

105105105151515777AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=15 AB=CD=15

AC=BD=7 AC=BD=7

Now let's calculate all the sides together to find the perimeter of the rectangle:

7+15+7+15=14+30=44 7+15+7+15=14+30=44

Answer

44

Exercise #9

The area of the rectangle below is equal to 18.

Calculate the perimeter of the rectangle.

181818666333AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=6 AB=CD=6

AC=BD=3 AC=BD=3

To calculate the perimeter of the rectangle, we add all the sides together:

3+6+3+6=6+12=18 3+6+3+6=6+12=18

Answer

18

Exercise #10

The area of a rectangle is equal to 70.

Calculate the perimeter of the rectangle.

707070101010777AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=10 AB=CD=10

AC=BD=7 AC=BD=7

Now we can calculate the perimeter of the rectangle by adding all the sides together:

7+10+7+10=14+20=34 7+10+7+10=14+20=34

Answer

34

Exercise #11

The area of the rectangle below is equal to 96.

Calculate the perimeter of the rectangle.

969696121212888AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=12 AB=CD=12

AC=BD=8 AC=BD=8

Now we can calculate the perimeter of the rectangle by adding all the sides together:

8+12+8+12=16+24=40 8+12+8+12=16+24=40

Answer

40

Exercise #12

The area of the rectangle shown below is equal to 10.

Calculate the perimeter of the rectangle.

101010555222AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=5 AB=CD=5

AC=BD=2 AC=BD=2

Now we can calculate the perimeter of the rectangle by adding all the sides together:

2+5+2+5=4+10=14 2+5+2+5=4+10=14

Answer

14

Exercise #13

The area of the rectangle is 112.

Calculate the perimeter of the rectangle.

112112112141414888AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=14 AB=CD=14

AC=BD=8 AC=BD=8

Now we can calculate the perimeter by adding all the sides together:

8+14+8+14=16+28=44 8+14+8+14=16+28=44

Answer

44

Exercise #14

The area of the rectangle below is 63.

Calculate the perimeter of the rectangle.

636363999777AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=9 AB=CD=9

AC=BD=7 AC=BD=7

Now we can calculate the perimeter of the rectangle by adding all the sides together:

7+9+7+9=14+18=32 7+9+7+9=14+18=32

Answer

32

Exercise #15

The area of a rectangle is 78.

Calculate the perimeter of the rectangle.

787878131313666AAABBBDDDCCC

Video Solution

Step-by-Step Solution

Since in a rectangle every pair of opposite sides are equal to each other, we can claim that:

AB=CD=13 AB=CD=13

AC=BD=6 AC=BD=6

Now we can calculate the perimeter of the rectangle by adding all the sides together:

6+13+6+13=12+26=38 6+13+6+13=12+26=38

Answer

38

Exercise #16

Look at the rectangle in the figure.

P=30P=30P=30555

Its perimeter is 30 cm.

What is its area?

Video Solution

Step-by-Step Solution

The perimeter of the rectangle equals the sum of all its sides, which means:

P=AB+BC+CD+DA P=AB+BC+CD+DA

Since in a rectangle each pair of opposite sides are equal, we can say that:

BC=AD=5 BC=AD=5

This means that the two sides together equal 10, and now we'll subtract them from the perimeter and get:

AB+DC=3010=20 AB+DC=30-10=20

This means sides AB and DC together equal 20, and since they are equal to each other, we'll divide 20 to find out how much each one equals:

20:2=10 20:2=10

Now we'll multiply side AB by side BC to find the area of the rectangle:

10×5=50 10\times5=50

Answer

50 cm²

Exercise #17

ABCD is a rectangle.

BC = 5

Perimeter = 40

Calculate the area of the rectangle.

555AAABBBCCCDDD

Video Solution

Step-by-Step Solution

The perimeter of the rectangle equals:

P=AB+BC+CD+DA P=AB+BC+CD+DA

Since we know that BC equals 5 and in a rectangle opposite sides are equal to each other, we get:

40=AB+5+CD+5 40=AB+5+CD+5

40=10+AB+CD 40=10+AB+CD

Since AB equals CD we can write the equation as follows:

40=2AB+10 40=2AB+10

Let's move 10 to the other side and change the sign accordingly:

4010=2AB 40-10=2AB

30=2AB 30=2AB

Let's divide both sides by 2:

15=AB 15=AB

Now we know the length and width of the rectangle and can calculate its area:

15×5=75 15\times5=75

Answer

75

Exercise #18

The area of the square whose side length is 4 cm is
equal to the area of the rectangle whose length of one of its sides is 1 cm.

What is the perimeter of the rectangle?

Video Solution

Step-by-Step Solution

After squaring all sides, we can calculate the area as follows:

42=16 4^2=16

Since we are given that the area of the square equals the area of the rectangle , we will write an equation with an unknown since we are only given one side length of the parallelogram:

16=1×x 16=1\times x

x=16 x=16

In other words, we now know that the length and width of the rectangle are 16 and 1, and we can calculate the perimeter of the rectangle as follows:

1+16+1+16=32+2=34 1+16+1+16=32+2=34

Answer

34