The sum of the interior angles in a polygon increases as the number of sides increases.

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

Let's look at this hexagon.

Choose any one corner.

Draw diagonals from the chosen corner to form triangles.

There are 4 triangles inside the hexagon.

4 x 180º = 720º

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

No. of triangles = No. of sides - 2

**Example**

Find the number of sides in a polygon whose interior angle sum is 720º.

**Answer**

720 ÷ 180 = 4

No. of sides = No. of triangles + 2

No. of sides = 4 + 2 = **6**