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.

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.

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

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

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: