Cube – Definition With Examples

What is a Cube?

A cube is a solid shape with six square faces. Each square face has the same side length and thus all the faces have the same size. 

A cube has 12 edges and 8 vertices. Each vertex refers to a corner where three edges of a cube meet. 

We can observe several examples of the cube shape in our everyday life. Cube shaped objects include sugar cubes, rolling dice, ice cubes, and the world-famous Rubik’s Cube!

Let’s explore the properties and the role of the cube in mathematics and in real life. 

Properties of a Cube Shape 

• It is a three-dimensional, square-shaped figure
• It has 6 faces, 12 edges, and 8 vertices
• All faces are in the shape of a square
• All sides have the same length 
• Each vertex meets three faces and three edges 
• The edges run parallel to those parallel to it
• All angles of a cube are right angles 

Surface Area of a Cube

The total surface area of a cube is defined as the area of its outer surface. 

Since the cube has six square faces and each of the square faces is of the same size, the total surface area of a cube = 6 ✕ area of one face.

Let’s say the length of each edge is “a”.

Area of one square face = edge ✕ edge = a ✕ a = a²

Therefore, the total surface area of the cube = 6a²

The total surface area of the cube will be equal to the sum of all six faces of the cube. 

The Lateral Surface Area of a Cube 

Imagine yourself sitting in a cube shaped room. You can then see the four walls around you. This denotes the lateral surface area of that room. That is, the lateral surface area of a cube shaped room is the area of its four walls, excluding the ceiling and the floor.

The lateral surface area of the cube is the sum of areas of its square faces, excluding the area of the top and the bottom face.

So the lateral surface area of a cube = sum of areas of 4 faces = 4a² 

The Volume of a Cube 

The volume of a three-dimensional object can be defined as its capacity or the amount of liquid it could hold if it was hollow from the inside. 

The volume is calculated by multiplying the object’s length, breadth, and height. In the case of a cube shape, the length, width, and height are all of the same length. Let us refer to it as “a”.

Hence the volume of the cube is a ✕ a ✕ a = a³  

Solved Examples

Example 1: The value of each side of a cube is 20 cm. What is the surface area of the cube? 

Solution: Let’s use the formula to calculate the surface area where the value of each side is a.

Surface area of the cube = 6a² = 6 ✕ 400 = 2400 cm²

Example 2: The value of each side of a cube is 10 cm. What is the volume of the cube? 

Solution: Let’s use the formula to calculate the volume of the cube, where each side is a. 

Volume of the cube = a³ = 10 × 10 × 10 = 1000 cm³

Example 3: A cube shaped container with a side of 2 m is to be painted. What is the total surface area to be painted? 

Solution: Since each side is 2 m, we will use the formula,  6 ✕ (Side)²Hence, the total surface area to be painted = 6 ✕ 4 = 24 m²

Practice Problems

Frequently Asked Questions