## Why do Angles in a Triangle Add to 180 Degrees?

To investigate the sum of the angles in a triangle, we can begin by marking each angle with a different colour.

We can use this to find out what the angles in a triangle add up to.

If we move these angles so that they fit in next to each other, we can see that they rest on a straight line.

**Angles on a straight line add up to 180°**.

Therefore, **angles in a triangle also add up to 180°**.

You can test this at home by following these steps:

1) Cut out a triangle

2) Mark the outer angles

3) Cut these angles off

4) Place these marked angles together

You should be able to place these angles onto a straight line.

**Angles in a triangle add up to 180°**.