CBSE Class 6 Maths Revision Notes Chapter 2 Lines and Angles

Lines and Angles introduce students to the basic building blocks of geometry, including points, line segments, lines, rays and angles. In CBSE Class 6 Maths Chapter 2, students learn how angles are formed, compared, measured, drawn and classified.

Class 6 Maths Chapter 2 Lines and Angles helps students understand the language of geometry. A dot on paper, the edge of a book, a beam of light, the hands of a clock and the opening of a door can all be studied using this chapter.

These CBSE Class 6 Maths Revision Notes Chapter 2 for the 2026–27 academic year cover key concepts such as points, line segments, lines, rays, angles, measuring angles, drawing angles and types of angles. The notes are arranged for quick revision, classroom learning and exam preparation.

Key Takeaways

• Point: A point shows an exact location and has no length, breadth or height.
• Line segment: A line segment joins two points and has two endpoints.
• Angle: An angle is formed when two rays start from the same point.
• Protractor: A protractor is used to measure and draw angles in degrees.

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Access Class 6 Maths Chapter 2 Lines and Angles Notes in 30 Minutes

Use this quick order to revise the chapter:

This order helps students move from simple geometry ideas to angle measurement and classification.

Lines and Angles Class 6 Notes: Key Terminologies and Concepts

This chapter begins with basic terms used in geometry. These terms help students understand shapes, diagrams, constructions and measurements in later classes.

Point

A point marks an exact location.

It has no length, no breadth and no height. It is shown by a small dot and named using a capital letter.

Examples:

• Point A
• Point P
• Point Z

Objects such as the tip of a pencil, tip of a needle or point of a compass give the idea of a point.

Line Segment

A line segment is the shortest path between two points.

It has two endpoints. If the endpoints are A and B, the line segment is written as AB or BA.

Examples of line segments:

• Edge of a ruler
• Side of a notebook
• Edge of a table
• Side of a square

Line

A line is formed when a line segment is extended endlessly in both directions.

A line has no fixed length and no endpoints. A line through points A and B can be written as AB. It can also be named using a small letter, such as line l or line m.

Only one line can pass through two given points.

Ray

A ray starts from one point and goes endlessly in one direction.

The starting point is called the initial point. If a ray starts at A and passes through B, it is written as ray AB.

Examples of rays:

• Sun rays
• Torch light
• Beam from a lighthouse

The order of letters is important in naming a ray. Ray AB starts at A, while ray BA starts at B.

Difference Between Line Segment, Line and Ray

Angle

An angle is formed when two rays start from the same point.

The common starting point is called the vertex. The two rays are called the arms of the angle.

For example, if rays BD and BE start from point B, then B is the vertex and BD and BE are the arms.

The angle can be named as:

∠DBE or ∠EBD

The vertex is always written in the middle.

Vertex and Arms of an Angle

An angle is about rotation or turn. It does not become larger because its arms are longer.

Drawing a 30° Angle Using a Protractor

Drawing angles is an important skill in Class 6 Maths Chapter 2 Lines and Angles. A protractor helps draw an angle of a given measure.

Let us draw ∠TIN = 30°.

Step 1: Draw the Base Ray

Draw a ray and name it IN.

Point I will be the vertex of the angle.

Step 2: Place the Protractor

Place the centre point of the protractor on I.

Align ray IN with the 0° mark of the protractor.

Step 3: Mark 30°

Starting from 0°, count up to 30° on the correct scale.

Mark a point and name it T.

Step 4: Join the Point and Complete the Angle

Use a ruler to join I and T.

Now, ∠TIN = 30°.

Measuring Angles in Class 6 Maths Chapter 2

Angles are measured in degrees.

The symbol for degree is °.

A full turn is divided into 360 equal parts. Each part is called 1 degree.

Important Angle Measures

What Is a Protractor?

A protractor is a geometry tool used to measure and draw angles.

A usual school protractor is shaped like a half circle. It is marked from 0° to 180°.

How to Measure an Angle Using a Protractor

Follow these steps:

1. Place the centre of the protractor on the vertex of the angle.
2. Align one arm of the angle with the 0° line.
3. See where the other arm meets the degree scale.
4. Read the correct scale.
5. Write the answer with the degree symbol.

Why Does a Protractor Have Two Scales?

A protractor has two scales so that angles can be measured from the left side or the right side.

Always start reading from the 0° mark aligned with one arm of the angle.

If the angle opens from the right, use the scale starting from the right 0°.

If the angle opens from the left, use the scale starting from the left 0°.

Common Protractor Check

Comparing Angles by Superimposition

Superimposition means placing one angle over another to compare their sizes.

To compare two angles:

1. Place the vertex of one angle over the vertex of the other.
2. Match one arm of both angles.
3. Observe the position of the second arm.
4. The angle with the wider opening is larger.

Smaller, Larger and Equal Angles

Why Arm Length Does Not Decide Angle Size

The size of an angle depends on the amount of rotation between its arms.

Longer arms do not make an angle bigger. Shorter arms do not make an angle smaller.

If the opening is the same, the angle is the same.

Comparing Angles Without Superimposition

Sometimes it is not possible to place one angle directly over another. In such cases, angles can be compared using a transparent circle.

Using a Transparent Circle

Steps:

1. Place the centre of the transparent circle on the vertex of the first angle.
2. Mark where both arms meet the circle.
3. Place the circle on the second angle.
4. Match one arm and compare the second arm.

This method helps compare angles even when they cannot be moved or traced easily.

Using Rotating Arms

Rotating arms can be made using two straws and a paper clip.

When the straws rotate, they form different angles. Students can compare these angles by placing one rotating arm over another.

This activity shows that angles are formed by turning.

Types of Angles in Lines and Angles Class 6 Notes

Angles are classified according to their measures.

The main types of angles are:

• Acute angle
• Right angle
• Obtuse angle
• Straight angle
• Reflex angle

Acute Angle

An acute angle is greater than 0° and less than 90°.

Examples:

30°, 45°, 60°

An acute angle looks sharp.

Right Angle

A right angle measures exactly 90°.

It looks like the corner of a square or rectangle.

Examples:

• Corner of a notebook
• Corner of a window
• Edge of a classroom board

Two lines meeting at a right angle are called perpendicular lines.

Obtuse Angle

An obtuse angle is greater than 90° and less than 180°.

Examples:

110°, 120°, 150°

An obtuse angle is wider than a right angle but smaller than a straight angle.

Straight Angle

A straight angle measures exactly 180°.

It forms a straight line.

A straight angle is half of a full turn.

Reflex Angle

A reflex angle is greater than 180° and less than 360°.

Examples:

210°, 270°, 300°

It is bigger than a straight angle but smaller than a full turn.

Types of Angles Table

Important Topics of Class 6 Maths Chapter 2 Lines and Angles You Shouldn’t Miss

1. Basic Geometry Terms

Students should know the meaning of point, line segment, line and ray.

These terms are used throughout geometry.

2. Naming Angles Correctly

When naming an angle with three letters, the vertex should always be in the middle.

Example:

∠ABC has B as the vertex.

3. Comparing Angles

Angles can be compared by superimposition or by using a transparent circle.

Students should remember that angle size depends on rotation, not arm length.

4. Measuring Angles

Angles are measured in degrees.

A protractor is used to measure them accurately.

5. Drawing Angles

Students should know how to draw angles such as 30°, 40°, 75°, 90° and 110° using a protractor.

6. Types of Angles

Students should be able to identify acute, right, obtuse, straight and reflex angles by their degree measures.

Importance of Maths Chapter 2 Lines and Angles Class 6 Notes

Lines and Angles is important because it introduces the basic language of geometry.

Students use these concepts in later chapters on triangles, quadrilaterals, polygons, symmetry, perimeter, area and construction.

The chapter also improves visual thinking. Students learn to observe shapes, compare openings, measure turns and draw accurate figures.

Angles also appear in real life. They are seen in clocks, doors, scissors, roads, swings, ramps, ladders, buildings and maps.

Tips for Learning Class 6 Maths Chapter 2 Lines and Angles

Understand the Basic Terms First

Do not start with angle measurement before understanding point, line segment, line and ray.

These are the base of the chapter.

Practise Naming Angles

Write the vertex in the middle while naming an angle.

For example, if B is the vertex, write ∠ABC or ∠CBA.

Use a Protractor Carefully

Place the centre on the vertex.

Align one arm with 0°.

Read the correct scale.

Look for Angles Around You

Find angles in clocks, books, doors, scissors, windows and swings.

This makes the chapter easier to understand.

Draw Different Types of Angles

Practise drawing acute, right, obtuse, straight and reflex angles.

Drawing helps students remember the difference between angle types.

Solved Examples Based on Lines and Angles

Example 1: Classify the Angle 65°

65° is greater than 0° and less than 90°.

So, it is an acute angle.

Answer: 65° is an acute angle.

Example 2: Classify the Angle 130°

130° is greater than 90° and less than 180°.

So, it is an obtuse angle.

Answer: 130° is an obtuse angle.

Example 3: Find the Angle Between Two Consecutive Clock Numbers

A clock has 12 equal parts.

A full turn is 360°.

So:

360° ÷ 12 = 30°

Answer: The angle between two consecutive clock numbers is 30°.

Example 4: Find the Angle at 3 o’clock

At 3 o’clock, the minute hand is at 12 and the hour hand is at 3.

There are 3 spaces between 12 and 3.

Each space is 30°.

So:

3 × 30° = 90°

Answer: The angle at 3 o’clock is 90°.

Example 5: Find the Reflex Angle

If the smaller angle is 80°, find the reflex angle.

A full turn is 360°.

Reflex angle = 360° - 80°

= 280°

Answer: The reflex angle is 280°.

Quick Revision Summary for Lines and Angles

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