When you learn to find the area of regular polygons, you are given a formula (A=½ap) that uses something called the "apothem". This video explains how to find the apothem using either SohCahToa or special triangles.
Finding Area of Regular Polygons
This video explains how to find area of polygons using the apothem formula: A=½ap. It also shows you how to find polygon area in a way that you'll actually remember by the time your final rolls around.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)