# WHY must a pentagon add up to 540° (in pictures)

Because there are now 3 triangles in a pentagon, it must add up to `3times180°=540°`

The pentagon can be made from 3 triangles.

**Example 1**

An equilateral pentagon will have 5 equal internal angles and would be

`540^circ/5=108^circ`

Each internal angle is 108°.

But the interior angles would still add up to 540°.