Mathematics Class 4 - Geometry Notes

Geometry

Welcome to the chapter on Geometry for Class 4. In this chapter, you will learn about shapes, lines, angles, and their properties. By the end of this chapter, you will be able to identify, draw, and describe different geometric figures and understand their uses in daily life!

Introduction

Geometry is the study of shapes and their properties. We see many shapes around us, like squares, circles, rectangles, and triangles. Geometry helps us understand how these shapes work and how to use them.

Basic Geometric Shapes

• Square: Four equal sides and four corners.
• Rectangle: Opposite sides are equal and four corners.
• Triangle: Three sides and three corners.
• Circle: No sides or corners, round shape.
• Polygon: A shape with many sides (like pentagon, hexagon).

Lines and Angles

• Line: A straight path that goes on forever in both directions.
• Line Segment: A part of a line with two endpoints.
• Ray: A part of a line with one endpoint.
• Angle: Made when two lines meet at a point.

Types of Angles

• Right Angle: Exactly 90°.
• Acute Angle: Less than 90°.
• Obtuse Angle: More than 90° but less than 180°.
• Straight Angle: Exactly 180°.

Perimeter and Area

• Perimeter: The distance around a shape.
• Area: The space inside a shape.

Example: To find the perimeter of a rectangle, add all its sides. To find the area, multiply its length by its width.

Fun Activity: Shape Hunt!

Look around your home or classroom. Find objects that are squares, rectangles, circles, or triangles. Draw them and label their shapes!

Summary

• Geometry is about shapes, lines, and angles.
• We use geometry in drawing, building, and designing things.
• Knowing about perimeter and area helps us measure shapes.

Practice Questions

1. How many sides does a hexagon have?
2. What is the perimeter of a square with sides of 5 cm?
3. Name a shape with three sides.
4. What is a right angle?
5. How do you find the area of a rectangle?

Challenge Yourself

• Draw a triangle, rectangle, and circle. Label their sides and corners.
• Find the perimeter and area of a rectangle with length 6 cm and width 4 cm.

Did You Know?

• The Great Pyramid of Giza is a giant geometric shape!
• Circles have no corners or sides.

Glossary

• Geometry: The study of shapes and their properties.
• Angle: The space between two lines that meet.
• Perimeter: The distance around a shape.
• Area: The space inside a shape.

Answers to Practice Questions

1. Six
2. 20 cm (5 + 5 + 5 + 5)
3. Triangle
4. An angle of 90°
5. Multiply length by width

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Explore the world of shapes and angles—geometry is everywhere!