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Geometry - properties of shapes

Right angles, acute and obtuse angles

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Explainer Video

Tutor: Holly

Summary

Right angles, acute and obtuse angles

In a nutshell

Angles are measured in degrees ( $\degree$ ). A right angle measures 90 $\degree$ , and can be used to describe turns.

Right angles and turns

A right angle measures 90 $\degree$ . You can measure angles with a protractor. A right angle can also be described as a quarter of a turn.

Maths; Geometry - properties of shapes; KS2 Year 3; Right angles, acute and obtuse angles

If you turn around once fully, you will have turned 360 $\degree$ . Therefore:

1 right angle makes a quarter turn.
2 right angles make a half-turn.
3 right angles make three quarters of a turn.
4 right angles make a full turn.

Note: A half-turn (180 $\degree$ ) is also called an "angle on a straight line".

Other angles

Apart from right angles, there are other angles to consider:

Acute angles are less than 90 $\degree$ :

Obtuse angles are greater than 90 $\degree$ but less than 180 $\degree$ :

Reflex angles are more than 180 $\degree$ but less than 360 $\degree$ :

Here are all the angles together:

Learn with Basics

Length:

Unit 1