Calculate Missing Interior Angles of Polygons

In this activity, we will calculate the missing angles inside irregular polygons.

 

An irregular polygon does not have all the same angles and sides unlike a regular polygon. 

 

Regular hexagon                  Irregular hexagon

 

The Sum of the Interior Angles of any Polygon:

 

 

Therefore, we can work out the sum of angles of any polygon using this rule!

 

Let's try a question!

 

Example

Calculate the sum of the interior angles in a heptagon.

 

 

Answer

We know that a heptagon has seven sides.

 

 

It splits into five triangles (5 x 180) or we can use our rule:

 

 

Sum = 180 x (7 sides - 2)

Sum = 180 x 5

Sum = 900^o

 

Let's do some questions!