Angles

There are in a complete turn. So in half a turn there are , and in a quarter of a turn .

We sometimes call a quarter of a turn a right angle, and mark it with a square

We can use these facts to solve simple problems. Here are some examples:

 

 

Different types of angle

These are the different types of angle:

Any angle that is less than is called an acute angle.

Any angle which is between and is called an obtuse angle.

Any angle that is between and is called a reflex angle.

You also need to remember that the angles in a triangle add up to , and that the angles in a quadrilateral add up to .