A polygon is just a “many sided shape”. A regular polygon is one where all the angles and sides are the same (if they are different you have an irregular polygon).**Names Of Regular Polygons**

- 3 sided – equilateral triangle
- 4 sided – square
- 5 sided – pentagon
- 6 sided – hexagon
- 7 sided – heptagon
- 8 sided – octagon
- 9 sided – nonagon
- 10 sided – decagon

Even if this does not come up directly in the exam, it might help you in pub quizzes later in life.**Interior and Exterior Angles**Interior angles are just the angles inside a shape, the exterior angles are the angles between the shape and the adjacent angle if a side was extended outwards….that sounds complicated but it’s pretty easy if you look at the diagram above.

There are some rules about these that apply to **ANY POLYGON:**

- The sum of the exterior angles is 360°
- The sum of the interior angles is (n – 2) x 180 ° – where n is the number of sides

There are some rules that apply only to **REGULAR POLYGONS:**

- Any given exterior angle equals 360° divided by n
- Any interior angle equals 180° minus the exterior angle