**Angles** measure the **amount of rotation** in degrees between two straight lines.

Here are **four types** of angle:

1) A right angle

- Right angles measure
**90 degrees**. - They form an
**L shape**. **The symbol**for a right angle is shown in the diagram above.

2) An acute angle

Acute angles measure between **0 and 90 degrees**.

3) An obtuse angle

Obtuse angles measure between **90 and 180 degrees**.

4) A reflex angle

Reflex angles measure between **180 and 360 degrees**.

There are **4 rules** for you to learn about angles:

1) Angles around a point add up to **360 degrees**

The above angles added together = **360°**. This is true for any angles **around a point**.

2) Angles on a straight line add up to **180 degrees**

The above angles add up to **180°**. This is true for all angles **on a straight line**.

3) Angles in a triangle add up to **180 degrees**

The above angles add up to **180°**. Remember the right angle in the above diagram is worth **90°**. Inside **all triangles** the angles will always **add up to 90°**.

4) Angles in a quadrilateral (any 4-sided shape) add up to **360 degrees**.

In the above quadrilateral **all the angles added together equal 360°**. This is true for **all four sided shapes**.

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