Class 6 Mathematics

Chapter 4: Basic Geometrical Ideas

STAGE 0: Foundation

Geometry is the study of shapes and figures 😊

We see geometry everywhere:

Doors and windows
Roads and bridges
Wheels and clocks

In this chapter, we learn about:

Points, lines, and curves
Angles
Triangles
Circles

STAGE 1: Concepts Explained

Point

A point shows a position. It has no length or breadth.

Line

A line is a straight path that goes on endlessly in both directions.

Line Segment

A line segment has two fixed end points.

Ray

A ray starts at one point and goes on in one direction.

Curves

A curve is a line that is not straight.

Angle

An angle is formed when two rays meet at a common point.

Types of Angles

Acute angle (less than 90°)
Right angle (90°)
Obtuse angle (more than 90°)

Triangle

A triangle has three sides and three angles.

Types of Triangles

Equilateral triangle (all sides equal)
Isosceles triangle (two sides equal)
Scalene triangle (all sides different)

Circle

A circle is a round shape.

Parts of a Circle

Centre
Radius
Diameter
Chord

STAGE 2: Solved Examples

Example 1:
Name the figure that has two end points.

Solution:
A line segment has two end points.

Example 2:
What type of angle is 90°?

Solution:
90° is a right angle.

Example 3:
Name a triangle with all sides equal.

Solution:
Equilateral triangle.

STAGE 3: Practice Questions

1. Name the figure that has no end points.
2. What is a ray?
3. Name any two types of angles.
4. How many sides does a triangle have?
5. Name any two parts of a circle.

STAGE 4: Quick Revision

A point shows position
A line has no end points
An angle is formed by two rays
A triangle has three sides
A circle is round in shape

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Class 6 Mathematics – Learn Without Fear

Class 6 Mathematics – Complete NCERT Library

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