Maths

Angles - Foundation

There are 360° in a complete turn. So in half a turn there are 180°, and in a quarter of a turn 90°.

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:

- Question
Find angle a in this diagram:

- Answer
The answer is

**110°**.All the angles add up to 360° (a complete turn).

So a = 360° - 60° - 100° - 90° = 110°.

Remember that a right angle (90°) can be marked with a square.

- Question
Find angle b in this diagram.

- Answer
The answer is

**100°**.The angles make a straight line (half a turn).

So b = 180° - 50° - 30° = 100°.

- Question
Find angle c in this diagram.

- Answer
The answer is 70°.

The two angles make a right angle.

So c = 90° - 20° = 70°

For your exam, you will need to know the following types of angle:

Any angle that is less than 90° is called an **acute** angle.

Any angle which is between 90° and 180° is called an **obtuse** angle.

Any angle that is between 180° and 360° is called a **reflex** angle.

You also need to remember that the angles in a triangle add up to 180°, and that the angles in a quadrilateral add up to 360°.

p + q + r = 180° w + x + y + Z = 360°

**Now try a **Test Bite