Angles

Types of Angles for Class 5 maths

This discussion is about different types of angles in class 5. Here students will be introduced to different angles like acute angle, right angle and obtuse angle.

In this learning concept, the students will also learn to

Classify instrument for measuring angles.
Identify how to measure angles.
Evaluate how to measure angles with a protractor.

Each concept is explained to class 5 maths students using illustrations, examples, and mind maps. Students can assess their learning by solving the two printable worksheets given at the page’s end.

Download the types of angles worksheet for class 5 and check the solutions to the types of angles question for class 5 provided in PDF format.

An angle is defined as the figure formed by the intersection of two lines or rays.

Parts of Angles:

Arms of an Angle
- The two rays or the lines that meet at the common point to form an angle are called the arms of an angle.
Vertex of an Angle
- The point where the two arms meet is called the vertex of an angle.

In the figure, the ray OA and OB are the arms of an angle, and the point O is the vertex of an angle.

Naming Angles

The symbol that is used to name an angle is ∠.
The three ways to name an angle are:
- Using only the vertex point.
- Using the vertex and a point of each arm.
- Using an alphabet or numbers.

Using Only the Vertex

The vertex is at B.
The angle is named ∠B.
If two or more angles have the same vertex then the angle is not named by using only the vertex.

Using Only the Vertex and the Points of Each Arm

Three points are used to name the angle, one point on each arm and the vertex.
While naming an angle the vertex is kept in the middle.
The angle is named ∠CBA or ∠ABC.

Using the Alphabet or the Numbers

The angle is named as ∠1 or ∠a.
The lower-case English alphabet is used to name an angle.
If two or more angles have the same vertex then the angle is named by either using the vertex and point of each arm or by numbers or letters.

How to Measure Angles?

An angle is measured in degree.
The symbol of the degree is “°”.

What Is a Protractor?

The instrument used to measure an angle is called a protractor.
A protractor is semicircular in shape.
It has degrees marked on it from 0° to 180° clockwise in the outer scale and anticlockwise in the inner scale.

Angles in Our Surrounding

The image below shows the angle in real-life objects.

Types of Angles

Depending upon the measure of an angle, the angle is classified as

Acute angle
Right angle
Obtuse angle

What Is an Acute Angle?

Acute angle is defined as the angle which is more than 0° but less than 90°.

Examples:

What Is a Right Angle?

The right angle is defined as the angle which is equal to 90°.

Examples:

What Is an Obtuse Angle?

An obtuse angle is defined as the angle which is more than 90° but less than 180°.

Examples:

The Figures Below Show All the Three Angles Together.

How to Measure Angles With a Protractor?

Keep the protractor aligned to the base ray such that the base ray is at 0° or 180°.
The number where the protractor coincides with the second ray gives the measure of the angle.

Examples:

Measure the angle shown in the protractor.

Solution:

The image shows that one ray is at 0° and the other ray is at 110°.

Therefore, the angle shown on the protractor is 110°.