Chapter 4 · CBSE Class 8 Maths (NCERT Ganita Prakash Part 2)

Exploring Some Geometric Themes

Discover fractals like the Sierpinski triangle and Koch snowflake, and explore solid shapes, nets, and geometric constructions.

🔺 Chapter 4

4.1

Fractals: Repeating Patterns Forever

A fractal is a shape made of smaller copies of itself repeated infinitely. The Sierpinski triangle is formed by repeatedly removing the middle triangle from a larger one.

1

If a Sierpinski triangle starts with 1 triangle and each step triples the number of smaller triangles, how many triangles exist after 3 steps?

3³ = 27 triangles

2

What happens to the total area of a Sierpinski triangle as the number of steps increases?

The area shrinks toward zero, since each step removes 1/4 of the remaining area

4.2

Nets of Solid Shapes

A net is a 2D pattern that folds up into a 3D solid shape. Understanding nets helps visualize surface area and how solids are constructed.

1

How many faces does the net of a cube have?

6 square faces

2

What solid does a net with 1 rectangle and 2 triangles (as end caps) typically fold into?

A triangular prism

Practice

Exercises

1. If a fractal pattern quadruples the number of shapes at each step, how many shapes exist after 2 steps?

2. How many faces does the net of a triangular pyramid (tetrahedron) have?

3. What is the defining feature of any fractal shape?

4. A cube net has 6 squares. If each square has side 4 cm, find the total surface area shown by the net.

5. Why can the same 3D solid have more than one valid net?