You already know that the interior angles of a triangle add up to 180º.

Polygons with more sides have a larger sum of interior angles.

To work out the sum of the interior angles of a polygon with more sides, we choose one of the corners and split the polygon into triangles. Each triangle will contain 180°.

**Example**

Work out the sum of the interior angles of this hexagon.

**Answer**

Choose any one corner.

Draw diagonals from the chosen corner to form triangles.

There are 4 triangles inside the hexagon.

4 x 180° = 720°

The sum of the interior angles of a hexagon is **720**°**.**

**General Rule:**

When you have a shape with n sides, the number of triangles it can be split into is n-2

Once you have the number of triangles, we can simply multiply that by 180° to find the internal angles.

For example: A 5 sided shape can be split into 3 triangles, if you then multiply 3 by 180 you get that there are 540° in a 5 sided shape.