Class 5 Notes - Symmetry

Introduction

Symmetry is a fundamental concept in geometry that refers to the balanced and proportionate similarity of an object or shape. It plays a vital role in art, nature, and various fields of mathematics.

Types of Symmetry

Line Symmetry

A shape has line symmetry if one half of the shape is a mirror image of the other half when folded along a line. This line is called the line of symmetry.

  • Examples: Butterfly, Leaf, Equilateral Triangle.

Rotational Symmetry

A shape has rotational symmetry if it looks the same after being rotated by a certain angle around a central point.

  • Examples: Wheel, Fan Blades, Regular Polygons.

Reflectional Symmetry

This occurs when an object looks the same on both sides of a central axis, as seen in reflections in mirrors or water surfaces.

Lines of Symmetry in Common Shapes

  • Square: 4 lines of symmetry
  • Rectangle: 2 lines of symmetry
  • Equilateral Triangle: 3 lines of symmetry
  • Circle: Infinite lines of symmetry

Examples of Symmetry

Example 1: Find the number of lines of symmetry in a regular hexagon.

Solution: A regular hexagon has 6 lines of symmetry.

Real-Life Applications of Symmetry

  • Architecture and building designs
  • Nature (flowers, leaves, snowflakes)
  • Art and patterns
  • Designing logos and symbols

Conclusion

Symmetry is an essential concept in mathematics and daily life. Understanding symmetry helps in problem-solving, design, and appreciating the beauty of the world around us.