Cubes

🏆Practice cubes

A cube is a type of cuboid in which all three dimensions (length, width and height) are identical. All cubes are made up of of six identical squares.

To find the volume of a cube we must go through the same steps as to find the volume of an cuboid, that is:

Length (L) × Depth (W) × Height (H).

Since the length, width and height are all equal, we only need to know one of them to calculate the volume.

C -Calculation volume of a cube

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Test yourself on cubes!

einstein

A cube has a base area of 9 cm².

Is it possible to calculate the volume of the cube? If so, what is it?

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Example exercise: volume and surface area of a cube

We have a cube whose length is 2 2 cm and we are asked to find its volume and surface area.


Finding the volume of a cube

The volume of a cube is equal to length × width × height.

Since the length, width and height of a cube are all equal, in our case the width and height of our given cube will also be 2 2 cm. Therefore,

8=2×2×2 8=2\times2\times2


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Finding the surface area of a cube

To find the total surface area of a cube, we will first find the surface area of one of its faces and then multiply the result by 6 (remember that cubes are composed of six identical square faces).

The area of each square is
4=2×2 4=2\times2

Therefore, the surface area of the cube will be:

4×6=24cm 4×6=24\operatorname{cm}


If you found this article helpful, you may also be interested in the following:

How to calculate the area of an orthohedron - rectangular prism or cube.

How to Calculate the Volume of a Rectangular Prism (Orthohedron)

Orthohedron - rectangular prism

For a wide range of mathematics articles visit Tutorela's website.


Example exercises

Example exercise 1

What is the volume of the cube

Given that:

The length of each side of the given cube is equal to 3 3 cm.

Question:

What is the volume of the cube?

Solution:

The volume of a cube (and the volume of a cuboid) is equal to:

Length × Width × Height

Therefore the volume of the cube: =33=27 =3^3=27

Answer:

27 cm3 27~cm³


Do you know what the answer is?

Example exercise 2

Given that:

Exercise 2 What is the surface area of the cube?

Given a cube in which each face has a surface area of 6 6 cm.

Assignment:

What is the total surface area of the cube?

Solution:

The total surface area of the cube is the combined area of all of its faces, ie:

Face area

6×6=36 6\times6=36

Answer:

36 cm2 36~cm²


Example exercise 3

Exercise 3 - What is the length of the diagonal of the face?

Given that:

In the given cube, the length of each edge is equal to 33 cm.

Question:

What is the length of the diagonal of the face?

Solution:

To solve this question we will use the Pythagorean Theorem to find the length of the diagonal of the face:

A2+B2=C2 A^2+B^2=C^2

Or, in our case:

Edge2+Edge2=Diagonal2 Edge^2+Edge^2=Diagonal^2

=32+32 =3^2+3^2

=18 =18

18=3×2=diagonal \sqrt{18}=3\times\sqrt{2}=diagonal

Answer:

323\sqrt{2}


Check your understanding

Example exercise 4

Exercise 4 - Given a cube whose edge length is equal to 5 cm

Given a cube whose edge length is equal to 5 5 cm.

Task:

Find the volume of the cube.

Solution:

The volume of the cube is equal to the length of the face of the cube to the power of 3 3

We can write it like this:

53=125 5^3=125

Answer:

125 cm3 125~cm³


Example exercise 5

Exercise 5 Given a cube whose volume equals 112 cc

Given a cube whose volume is equal to 112 112 cm³

Question:

How many whole cubes with a volume of 10 10 cm³ can fit inside the given cube?

Solution:

We divide the volume of the large cube into 10 10 to find out how many cubes of 10 10 cm³ fit into the given cube:

11210=1115 \frac{112}{10}=11\frac{1}{5}

Since we are only asked about whole cubes, it is possible to enter 11 11 cubes into the cube whose volume is 112 112 cm³.

Answer:

11 11 cubes.


Do you think you will be able to solve it?

Review questions

What is a cube?

A cube is a cuboid with six square, equal faces (all the sides are equal).


How do we find the surface area of a cube?

To find the total surface area of a cube, all we need is the value of one of its sides (since all sides are equal).

Then, we find the surface area of one face by multiplying the side to the power of three.

Lastly, we multiply the surface area of one face by six (since cubes have six equal sides).

Example exercise

Task. Find the total surface area of the following given cube, which has a side length of 7cm 7\operatorname{cm}

How to calculate the surface area of a cube

Solution:

Let's start by finding the area of just one face:

Area=7cm×7cm=49cm2 Area=7\operatorname{cm}\times7\operatorname{cm}=49\operatorname{cm^2}

Now, let's multiply the area of one face by six to find the total surface area:

49cm2×6=294cm2 49\operatorname{cm^2}\times6=294\operatorname{cm^2}

Answer:

=294cm2 =294 \operatorname{cm^2}


Test your knowledge

What is the formula used to find the volume of a cube?

The find the volume of a cube, we multiply its three sides.

Remember: since each face is square, all its sides have the same length.

= = ,× \times

This formula can also be expressed as:

V=L3 V=L^3

since all the sides are equal.


Finding the volume of a cube: additional practice

Example 1

Task. Find the volume of a cube with a side length of4cm 4\operatorname{cm}

how to calculate the volume of the following cubes

Solution:

Using our formula, we get:

V=L3 V=L^3

V=(4cm)3=64cm3 V=\left(4\operatorname{cm}\right)^3=64\operatorname{cm^3}

Answer

V=64cm3 V=64\operatorname{cm^3}


Example 2

Task. Find the volume of a cube with a side length of 8cm 8\operatorname{cm}

Calculate the volume of the cube of edge

Solution:

Again, we will use our formula to find the volume:

V=L3 V=L^3

V=(8cm)3=512cm3 V=\left(8\operatorname{cm}\right)^3=512\operatorname{cm^3}

Answer

V=512cm3 V=512\operatorname{cm^3}


Do you know what the answer is?

Examples with solutions for Cubes

Exercise #1

If we increase the side of a cube by 6, how many times will the volume of the cube increase?

Video Solution

Step-by-Step Solution

Let's denote the initial cube's edge length as x,

The formula for the volume of a cube with edge length b is:

V=b3 V=b^3

therefore the volume of the initial cube (meaning before increasing its edge) is:

V1=x3 V_1=x^3

Now we'll increase the cube's edge by a factor of 6, meaning the edge length is now: 6x, therefore the volume of the new cube is:

V2=(6x)3=63x3 V_2=(6x)^3=6^3x^3

where in the second step we simplified the expression for the new cube's volume using the power rule for multiplication in parentheses:

(zy)n=znyn (z\cdot y)^n=z^n\cdot y^n

and we applied the power to each term in the parentheses multiplication,

Next we'll answer the question that was asked - "By what factor did the cube's volume increase", meaning - by what factor do we multiply the old cube's volume (before increasing its edge) to get the new cube's volume?

Therefore to answer this question we simply divide the new cube's volume by the old cube's volume:

V2V1=63x3x3=63 \frac{V_2}{V_1}=\frac{6^3x^3}{x^3}=6^3

where in the first step we substituted the expressions for the volumes of the old and new cubes that we got above, and in the second step we reduced the common factor between the numerator and denominator,

Therefore we got that the cube's volume increased by a factor of -63 6^3 when we increased its edge by a factor of 6,

therefore the correct answer is b.

Answer

63 6^3

Exercise #2

A cube has a base area of 9 cm².

Is it possible to calculate the volume of the cube? If so, what is it?

Video Solution

Answer

27 27

Exercise #3

A cube has a total of 14 edges.

Video Solution

Answer

False.

Exercise #4

A cube has edges measuring 3 cm.

What is the volume of the cube?

333

Video Solution

Answer

27 27

Exercise #5

All faces of the cube must be?

Video Solution

Answer

Squares

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