Examples with solutions for Surface Area of a Cuboid: Applying the formula

Exercise #1

Look at the cuboid below.

888555121212

What is the surface area of the cuboid?

Video Solution

Step-by-Step Solution

Let's see what rectangles we have:

8*5

8*12

5*12

Let's review the formula for the surface area of a rectangular prism:

(length X width + length X height + width X height) * 2

Now let's substitute all this into the exercise:

(8*5+12*8+12*5)*2=
(40+96+60)*2=
196*2= 392

This is the solution!
 

Answer

392 cm²

Exercise #2

A cuboid is shown below:

222333555

What is the surface area of the cuboid?

Video Solution

Step-by-Step Solution

Remember that the formula for the surface area of a cuboid is:

(length X width + length X height + width X height) 2

 

We input the known data into the formula:

2*(3*2+2*5+3*5)

2*(6+10+15)

2*31 = 62

Answer

62

Exercise #3

Look at the the cuboid below.

What is its surface area?

333555888

Video Solution

Step-by-Step Solution

First, we recall the formula for the surface area of a cuboid:

(width*length + height*width + height*length) *2

 

As in the cuboid the opposite faces are equal to each other, the given data is sufficient to arrive at a solution.

We replace the data in the formula:

 

(8*5+3*5+8*3) *2 =

(40+15+24) *2 =

79*2 = 

158

Answer

158

Exercise #4

Look at the cuboid below.

What is its surface area?

333333111111

Video Solution

Step-by-Step Solution

We identified that the faces are

3*3, 3*11, 11*3
As the opposite faces of an cuboid are equal, we know that for each face we find there is another face, therefore:

3*3, 3*11, 11*3

or

(3*3, 3*11, 11*3 ) *2

 

To find the surface area, we will have to add up all these areas, therefore:

(3*3+3*11+11*3 )*2

 

And this is actually the formula for the surface area!

We calculate:

(9+33+33)*2

(75)*2

150

Answer

150

Exercise #5

Calculate the surface area of the orthohedron below using the data in the diagram.

333555222

Video Solution

Step-by-Step Solution

To solve this problem, we'll utilize the formula for the surface area of a cuboid. The steps are as follows:

  • Step 1: Identify the dimensions from the problem. The dimensions provided are a=3a = 3, b=5b = 5, and c=2c = 2.
  • Step 2: Apply the surface area formula for a cuboid. The formula is: 2(ab+bc+ac) 2(ab + bc + ac) where aa, bb, and cc are the dimensions of the cuboid.
  • Step 3: Substitute the known values into the formula: 2(35+52+32) 2(3 \cdot 5 + 5 \cdot 2 + 3 \cdot 2)
  • Step 4: Calculate each term inside the parentheses: - ab=35=15 a \cdot b = 3 \cdot 5 = 15 - bc=52=10 b \cdot c = 5 \cdot 2 = 10 - ac=32=6 a \cdot c = 3 \cdot 2 = 6
  • Step 5: Sum the results from Step 4: 15+10+6=31 15 + 10 + 6 = 31
  • Step 6: Multiply the sum by 2 to find the total surface area: 2×31=62 2 \times 31 = 62

Thus, after performing the necessary calculations, the surface area of the orthohedron is 62 62 square units.

Answer

62

Exercise #6

Given the cuboid whose square base is of size 25 cm²,

The height of the cuboid is 3 cm,

333S=25

What is the surface area of the cuboid?

Video Solution

Step-by-Step Solution

Let's find the surface area of the cuboid step by step:

First, we determine the side length of the square base. Since the area of the square base is given as 25cm225 \, \text{cm}^2, we have:

s2=25    s=25=5cm s^2 = 25 \implies s = \sqrt{25} = 5 \, \text{cm}

Now, using the surface area formula for a cuboid with a square base:

Surface Area=2s2+4s×h \text{Surface Area} = 2s^2 + 4s \times h

Substitute the values s=5cms = 5 \, \text{cm} and h=3cmh = 3 \, \text{cm}:

Surface Area=2(52)+4(5)(3)=2(25)+60=50+60=110cm2 \text{Surface Area} = 2(5^2) + 4(5)(3) = 2(25) + 60 = 50 + 60 = 110 \, \text{cm}^2

Therefore, the surface area of the cuboid is 110 cm².

Answer

110 cm²

Exercise #7

Calculate the surface area of the box shown in the diagram.

Pay attention to the units of measure!

5 dm5 dm5 dm4 cm4 cm4 cm0.3 dm0.3 dm0.3 dm

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Convert all dimensions to the same unit.

  • Step 2: Apply the surface area formula for a cuboid.

  • Step 3: Calculate the total surface area.

Now, let's work through each step:

Step 1: Convert all dimensions to the same unit. For consistency, we will convert everything to decimeters (dm):

  • Width = 5 dm (already in dm)

  • Height = 4 cm. To convert cm to dm, divide by 10: 4cm=0.4dm 4 \, \text{cm} = 0.4 \, \text{dm} .

  • Depth = 0.3 dm (already in dm)

Step 2: Apply the surface area formula for a cuboid:

The surface area A A is given by:

A=2lw+2lh+2wh A = 2lw + 2lh + 2wh

Where:

  • l=0.3dm l = 0.3 \, \text{dm} (depth)

  • w=5dm w = 5 \, \text{dm} (width)

  • h=0.4dm h = 0.4 \, \text{dm} (height converted to dm)

Substitute these values into the formula:

A=2(0.3)(5)+2(0.3)(0.4)+2(5)(0.4) A = 2(0.3)(5) + 2(0.3)(0.4) + 2(5)(0.4)

Step 3: Calculate the surface area:

A=2(1.5)+2(0.12)+2(2) A = 2(1.5) + 2(0.12) + 2(2)

A=3+0.24+4 A = 3 + 0.24 + 4

A=7.24dm2 A = 7.24 \, \text{dm}^2

Note that the question requires the surface area in different units.

Thus, 7.24 dm² is 72.4 cm²

Therefore, the solution to the problem is 72.4 cm².

Answer

72.4 cm²

Exercise #8

An unfolded cuboid is shown below.

What is the surface area of the cuboid?

888111333

Video Solution

Step-by-Step Solution

To calculate the surface area of the rectangular prism, we will need to identify its three faces (each face appears twice):

1*3

1*8

3*8

 

The formula for the surface area of a rectangular prism is the sum of all the areas of the faces, that is:

We replace the data in the formula:

2*(1*3+1*8+3*8)=
2*(3+8+24) = 
2*35 = 

70

And this is the solution!

Answer

70

Exercise #9

The length of each edge in the cube is 8 cm.

Calculate the volume and area of the cube.

888

Video Solution

Step-by-Step Solution

To solve this problem, we will calculate the volume and surface area of a cube with edge length 8 cm.

  • Step 1: Calculate the volume of the cube using the formula V=a3 V = a^3 .

Given that the edge length a=8 a = 8 cm, the volume is calculated as follows:

V=83=8×8×8=512 cm3 V = 8^3 = 8 \times 8 \times 8 = 512 \text{ cm}^3

  • Step 2: Calculate the surface area of the cube using the formula S=6a2 S = 6a^2 .

Using the same edge length a=8 a = 8 cm, we find the surface area:

S=6×82=6×(8×8)=6×64=384 cm2 S = 6 \times 8^2 = 6 \times (8 \times 8) = 6 \times 64 = 384 \text{ cm}^2

Thus, the calculated volume and surface area of the cube are, respectively, 512 cm3^3 and 384 cm2^2.

Therefore, the correct solution to the problem, matching the given answer choices, is choice 1: V=512,S=384 V = 512, S = 384 .

Answer

V=512,S=384 V=512,S=384

Exercise #10

A rectangular prism has a square base measuring 25 cm.

It has a height is equal to 3 cm.

Calculate the surface area of the rectangular prism.

333

Video Solution

Answer

110