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Estimate the Size of Acute and Obtuse Angles

In this worksheet, students will use their knowledge to estimate an angle.

' Estimate the Size of Acute and Obtuse Angles' worksheet

Key stage:  KS 2

Year:  Year 5 Maths worksheets

Curriculum topic:   Geometry: Properties of Shapes

Curriculum subtopic:   Know Angles and Degrees

Popular topics:   Geometry worksheets

Difficulty level:  

Worksheet Overview

In this activity, we will learn how to estimate the size of each angle.

 

Remember:

Acute angles are smaller than 90°

Right angles are exactly 90°

Obtuse angles are larger than 90°

Reflex angles are larger than 180°

 

Let's try an example.

 

Example

Estimate the size of this angle.

 

Angle more than a right angle

Think of key angles such as: 30°, 60°, 90°, 120° and 180°

 

A right angle is 90°, so 30° is a third of a right angle and 60° is two thirds of a right angle.

A straight line is 180°, so 120° is a right angle plus a third of a right angle.

 

Answer

The angle is about one third more than a right angle

The angle is about 120°

Using a protractor, we would find that the exact size of this angle = 116°

 

a protractor

 

 

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