Three-dimensional figures

What are three-dimensional figures?

So far we have worked with common two-dimensional figures such as the square or the triangle.
Three-dimensional figures are those that extend into the third dimension, meaning that in addition to length and width, they also have height (that is, the figure has depth).


What differences do three-dimensional figures have?

Three-dimensional figures have several definitions that we will see next:
Below is a three-dimensional figure that we will use to learn each definition - The cube:

three-dimensional figure of a cube

Face: it is the flat side of a three-dimensional figure
In the cube we have here, there are 6 faces (one of them is painted gray)
Edge: these are the lines that connect one face to another in a three-dimensional figure
In the cube we have here, there are 12 edges (painted green)
Vertex: it is the point that connects the edges
In the cube we have here, there are 8 vertices (painted orange)

Volume: it is the amount of space contained within a three-dimensional figure.
The units of measurement are cm3 cm^3 .


Practice Cuboids

Examples with solutions for Cuboids

Exercise #1

Look at the cuboid below:

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What is the volume of the cuboid?

Video Solution

Step-by-Step Solution

To determine the volume of a cuboid, we apply the formula:

  • Step 1: Identify the dimensions of the cuboid:
    • Length (l l ) = 12 cm
    • Width (w w ) = 8 cm
    • Height (h h ) = 5 cm
  • Step 2: Apply the volume formula for a cuboid:

The formula to find the volume (V V ) of a cuboid is:

V=l×w×h V = l \times w \times h

Step 3: Substitute the given dimensions into the formula and calculate: V=12×8×5 V = 12 \times 8 \times 5

Step 4: Perform the multiplication in stages for clarity:

First, calculate 12×8=96 12 \times 8 = 96

Then multiply the result by 5: 96×5=480 96 \times 5 = 480

Therefore, the volume of the cuboid is 480cm3\mathbf{480 \, \text{cm}^3}.

Answer

480 cm³

Exercise #2

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 #3

A cuboid is shown below:

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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 #4

Given the cuboid of the figure:

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What is its volume?

Video Solution

Step-by-Step Solution

To solve this problem, we'll calculate the volume of the cuboid using the given dimensions:

  • Step 1: Identify the dimensions
  • Step 2: Apply the volume formula for a cuboid
  • Step 3: Calculate the volume

Let's work through these steps:

Step 1: From the diagram, we are informed of two dimensions directly: the width w=5 w = 5 and the height h=4 h = 4 . The diagram also indicates the horizontal length (along the base) is l=9 l = 9 .

Step 2: To find the volume of the cuboid, we use the formula:
Volume=length×width×height.\text{Volume} = \text{length} \times \text{width} \times \text{height}.

Step 3: Substituting the identified dimensions into the formula, we have:
Volume=9×5×4.\text{Volume} = 9 \times 5 \times 4.

Calculating this, we find:
9×5=45,9 \times 5 = 45,
45×4=180.45 \times 4 = 180.

Therefore, the volume of the cuboid is 180180 cubic units.

This corresponds to choice \#4: 180.

Answer

180

Exercise #5

Calculate the volume of the cuboid

If its length is equal to 7 cm:

Its width is equal to 3 cm:

Its height is equal to 5 cm:

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Video Solution

Step-by-Step Solution

The formula to calculate the volume of a cuboid is:

height*length*width

We replace the data in the formula:  

3*5*7

7*5 = 35

35*3 = 105

Answer

105 cm³

Exercise #6

Shown below is a cuboid with a length of 8 cm.

Its width is 2 cm and its height is 4 cm.

Calculate the volume of the cube.

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Video Solution

Step-by-Step Solution

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

  • Step 1: Identify the given dimensions of the cuboid.
  • Step 2: Apply the formula for the volume of a cuboid.
  • Step 3: Perform the calculation using the known dimensions.

Now, let's work through each step:
Step 1: The problem states that the cuboid has a length of 8 cm, a width of 2 cm, and a height of 4 cm.
Step 2: We will use the volume formula for a cuboid, which is:

V=length×width×height V = \text{length} \times \text{width} \times \text{height}

Step 3: Substituting the given dimensions into the formula, we have:

V=8cm×2cm×4cm V = 8 \, \text{cm} \times 2 \, \text{cm} \times 4 \, \text{cm}

Performing the multiplication:

V=16cm2×4cm=64cm3 V = 16 \, \text{cm}^2 \times 4 \, \text{cm} = 64 \, \text{cm}^3

Therefore, the volume of the cuboid is 64cm3 64 \, \text{cm}^3 .

Answer

64 cm³

Exercise #7

A cuboid is 9 cm long, 4 cm wide, and 5 cm high.

Calculate the volume of the cube.

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Video Solution

Step-by-Step Solution

To calculate the volume of the cuboid, we apply the formula for the volume of a cuboid:

V=length×width×height V = \text{length} \times \text{width} \times \text{height}

Given:

  • Length = 9 cm
  • Width = 4 cm
  • Height = 5 cm

Now, substituting the values into the formula:

V=9×4×5 V = 9 \times 4 \times 5

First, multiply 9 and 4:

9×4=36 9 \times 4 = 36

Then, multiply the result by 5:

36×5=180 36 \times 5 = 180

Therefore, the volume of the cuboid is 180 cm³.

Since this is a multiple-choice question, the correct choice is 4: 180 cm3 \text{180 cm}^3 .

Answer

180 cm³

Exercise #8

Below is a cuboid with a length of

8 cm.

Its width is 2 cm and its height is

4 cm.

Calculate the volume of the cube.

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Video Solution

Step-by-Step Solution

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

  • Step 1: Identify the given information
  • Step 2: Apply the appropriate formula for volume
  • Step 3: Perform the necessary calculations

Now, let's work through each step:

Step 1: The problem gives us the dimensions of a cuboid: length L=8cm L = 8 \, \text{cm} , width W=2cm W = 2 \, \text{cm} , and height H=4cm H = 4 \, \text{cm} .

Step 2: We'll use the formula to calculate the volume of a cuboid: V=L×W×H V = L \times W \times H .

Step 3: Substitute the given dimensions into the formula: V=8×2×4 V = 8 \times 2 \times 4 Calculate the result: V=16×4=64 V = 16 \times 4 = 64 Thus, the volume of the cuboid is 64cm3 64 \, \text{cm}^3 .

Therefore, the solution to the problem is 64cm3 64 \, \text{cm}^3 .

Answer

64 cm³

Exercise #9

A cuboid has a length of is 9 cm.

It is 4 cm wide and 5 cm high.

Calculate the volume of the cube.

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Video Solution

Step-by-Step Solution

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

  • Step 1: Identify the given dimensions: length = 9 cm, width = 4 cm, height = 5 cm.
  • Step 2: Apply the formula for the volume of a cuboid, V=length×width×height V = \text{length} \times \text{width} \times \text{height} .
  • Step 3: Calculate the value by substituting the given dimensions into the formula.

Now, let's work through each step:

Step 1: Given dimensions are:
- Length = 9 cm
- Width = 4 cm
- Height = 5 cm

Step 2: Use the formula for the volume of a cuboid:
V=length×width×height V = \text{length} \times \text{width} \times \text{height}

Step 3: Substitute the values into the formula:
V=9cm×4cm×5cm V = 9 \, \text{cm} \times 4 \, \text{cm} \times 5 \, \text{cm}

Calculate the product:
V=180cm3 V = 180 \, \text{cm}^3

Therefore, the volume of the cuboid is 180cm3 180 \, \text{cm}^3 .

Answer

180 cm³

Exercise #10

Look at the the cuboid below.

What is its surface area?

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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 #11

Look at the cuboid below.

What is its surface area?

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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 #12

An unfolded cuboid is shown below.

What is the surface area of the cuboid?

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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 #13

A cuboid has the dimensions shown in the diagram below.

Which rectangles form the cuboid?

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Video Solution

Step-by-Step Solution

Every cuboid is made up of rectangles. These rectangles are the faces of the cuboid.

As we know that in a rectangle the parallel faces are equal to each other, we can conclude that for each face found there will be two rectangles.

 

Let's first look at the face painted orange,

It has width and height, 5 and 3, so we already know that they are two rectangles of size 5x6

 

Now let's look at the side faces, they also have a height of 3, but their width is 6,

And then we understand that there are two more rectangles of 3x6

 

Now let's look at the top and bottom faces, we see that their dimensions are 5 and 6,

Therefore, there are two more rectangles that are size 5x6

 

That is, there are
2 rectangles 5X6

2 rectangles 3X5

2 rectangles 6X3

Answer

Two 5X6 rectangles

Two 3X5 rectangles

Two 6X3 rectangles

Exercise #14

Identify the correct 2D pattern of the given cuboid:

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Step-by-Step Solution

Let's go through the options:

A - In this option, we can observe that there are two flaps on the same side.

If we try to turn this net into a box, we should obtain a box where on one side there are two faces one on top of the other while the other side is "open",
meaning this net cannot be turned into a complete and full box.

B - This net looks valid at first glance, but we need to verify that it matches the box we want to draw.

In the original box, we see that we have four flaps of size 9*4, and only two flaps of size 4*4,
if we look at the net we can see that the situation is reversed, there are four flaps of size 4*4 and two flaps of size 9*4,
therefore we can conclude that this net is not suitable.

C - This net at first glance looks valid, it has flaps on both sides so it will close into a box.

Additionally, it matches our drawing - it has four flaps of size 9*4 and two flaps of size 4*4.

Therefore, we can conclude that this net is indeed the correct net.

D - In this net we can see that there are two flaps on the same side, therefore this net will not succeed in becoming a box if we try to create it.

Answer

999444444444444444444

Exercise #15

An orthohedron has the dimensions: 4, 7, 10.

How many rectangles is it formed of and what are their dimensions?

Video Solution

Step-by-Step Solution

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

  • Step 1: Identify the dimensions of each pair of rectangles given the orthohedron's dimensions.
  • Step 2: Each face of a cuboid corresponds to a rectangle, with three distinct pairs of dimensions.
  • Step 3: Identify all pairs of dimensions and count the pairs that form sets of rectangles.

Now, let's work through each step:
Step 1: The orthohedron's dimensions are given as 44, 77, and 1010.
Step 2: A cuboid (orthohedron) has three pairs of opposite rectangular faces:
- Pair 1: Two rectangles with dimensions 4×74 \times 7.
- Pair 2: Two rectangles with dimensions 4×104 \times 10.
- Pair 3: Two rectangles with dimensions 7×107 \times 10.
Step 3: Count each of the pairs to verify the total number of rectangles formed.
We find there are 6 rectangles in total, with the dimensions specified above fulfilling the conditions for each face of the cuboid.

The solution to the problem is that the orthohedron is formed of:
2 Rectangles 4×74 \times 7,
2 Rectangles 4×104 \times 10,
2 Rectangles 7×107 \times 10.

These dimensions and quantities match choice #3 in the answer options provided.

Answer

2 Rectangles 4X7

2 Rectangles 4X10

2 Rectangles 7X10