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Mathematics Class 7 - Visualising Solid-Shapes Notes

Comprehensive study notes for Class 7 - Visualising Solid-Shapes olympiad preparation

Visualising Solid Shapes

Welcome to the chapter on Visualising Solid Shapes for Class 7. In this chapter, you will learn about different solid shapes, their properties, and how to represent them in diagrams. By the end of this chapter, you will be able to identify, draw, and understand the features of various 3D shapes!

Introduction

Solid shapes are three-dimensional objects. Unlike flat shapes (2D), solid shapes have length, breadth, and height. We see solid shapes all around us, like boxes, balls, and pyramids.

Types of Solid Shapes

  • Cuboid: Like a box or a book.
  • Cube: All sides are equal, like a dice.
  • Cylinder: Like a can or a pipe.
  • Sphere: Like a ball.
  • Cone: Like an ice-cream cone.
  • Pyramid: Like the Egyptian pyramids.

Faces, Edges, and Vertices

  • Face: A flat surface of a solid shape.
  • Edge: Where two faces meet.
  • Vertex: A corner where edges meet.

Example: A cube has 6 faces, 12 edges, and 8 vertices.

Nets of Solid Shapes

A net is a flat pattern that can be folded to make a solid shape. Nets help us understand how the faces of a solid shape are arranged.

  • A cube’s net has 6 squares.
  • A cuboid’s net has 6 rectangles.

Drawing Solid Shapes

We use diagrams like isometric sketches and oblique sketches to show solid shapes on paper. These help us see all sides of a shape.

Views of Solid Shapes

  • Top View: How the shape looks from above.
  • Front View: How the shape looks from the front.
  • Side View: How the shape looks from the side.

Fun Activity: Make Your Own Solid Shape!

Cut out a net of a cube from paper. Fold and glue it to make your own cube!

Summary

  • Solid shapes have length, breadth, and height.
  • Common solid shapes are cube, cuboid, cylinder, sphere, cone, and pyramid.
  • Faces, edges, and vertices are important features of solid shapes.
  • Nets help us understand and make solid shapes.

Practice Questions

  1. How many faces does a cuboid have?
  2. Name a solid shape that has only one curved surface.
  3. What is a net of a cube?
  4. How many edges does a pyramid have?
  5. Draw the top, front, and side view of a cylinder.

Challenge Yourself

  • Make a net of a cuboid and fold it to form the shape.
  • List all the faces, edges, and vertices of a cone.

Did You Know?

  • Dice used in games are perfect cubes!
  • The Great Pyramid of Giza is one of the oldest solid shapes in the world.

Glossary

  • Solid Shape: A three-dimensional object.
  • Net: A flat pattern that can be folded into a solid shape.
  • Vertex: A corner point of a solid shape.
  • Edge: A line where two faces meet.
  • Face: A flat surface of a solid shape.

Answers to Practice Questions

  1. 6
  2. Sphere
  3. A net of a cube is made of 6 squares that can be folded to form a cube.
  4. Depends on the type of pyramid (a square pyramid has 8 edges).
  5. (Drawings required: Top view is a circle, front and side views are rectangles with curved sides.)

Explore solid shapes around you and try making your own models!

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