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What is a Cube?

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A cube has 6 equal square faces, 12 edges, and 8 vertices

A cube is a special three-dimensional shape with all sides of equal length. It's one of the five Platonic solids and is made up of:

6 faces - all identical squares
12 edges - all of the same length
8 vertices - corners where edges meet

Cubes are everywhere in our daily lives! You can find them in dice, sugar cubes, Rubik's cubes, and even buildings. Since all sides of a cube are equal, it's a very symmetrical and balanced shape.

Properties of a Cube

Image showing Cube properties
All edges are equal, all angles are 90 degrees

Cubes have special properties that make them unique among 3D shapes. Here are the key features:

Faces

6 identical square faces

Edges

12 edges of equal length

Vertices

8 vertices (corners)

Angles

All angles are right angles (90°)

Volume of a Cube

Image showing Cube volume calculation
Volume = side length × side length × side length

Volume tells us how much space a 3D shape takes up. For a cube, since all sides are equal, calculating volume is simple:

Volume Formula

V = s × s × s = s³

Where s is the length of one side of the cube

Let's try an example:

Example: Find the volume of a cube with side length 4 cm
Step 1: Identify side length → s = 4 cm
Step 2: Apply formula → V = 4 × 4 × 4
Step 3: Calculate → 64 cubic centimeters (cm³)

So a 4 cm cube has a volume of 64 cm³. That means 64 cubes of 1 cm each would fit inside it!

Surface Area of a Cube

Cube net showing all faces
A cube net shows all 6 faces that make up the surface

Surface area is the total area of all the faces of a 3D shape. Since a cube has 6 identical square faces:

Surface Area Formula

SA = 6 × s²

Where s is the length of one side

Let's calculate together:

Example: Find the surface area of a cube with side length 3 cm
Step 1: Area of one face → 3 × 3 = 9 cm²
Step 2: Multiply by 6 faces → 6 × 9 = 54 cm²

So the total surface area is 54 cm². This tells us how much material would be needed to cover the entire cube.

Diagonal of a Cube

Space diagonal in a cube
The space diagonal connects opposite corners through the cube

The diagonal of a cube is the longest straight line that can be drawn from one corner to the opposite corner, passing through the inside of the cube. We call this the "space diagonal".

The formula to calculate the diagonal is:

Diagonal Formula

d = s√3

Where s is the side length and √3 is approximately 1.732

Example calculation:

Example: Find the diagonal of a cube with side length 5 cm
Step 1: Apply formula → d = 5 × √3
Step 2: Calculate → 5 × 1.732 ≈ 8.66 cm

This diagonal is longer than the face diagonals because it goes through the entire cube.

Cube Knowledge Quiz

Test your understanding of cubes with this 5-question quiz. Choose the correct answer for each question.

1. How many faces does a cube have?
2. What is the volume of a cube with side length 2 cm?
3. If a cube has side length 3 cm, what is its surface area?
4. What shape are all faces of a cube?
5. What is the space diagonal of a cube with side length 1 cm?

Frequently Asked Questions

Here are answers to common questions about cubes:

Math Trivia

Discover interesting facts about cubes and geometry:

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