How to Decompose Polygons to Find the Area

By Bon Crowder

Decomposing polygons to find the area is something that you can do with a shape like a trapezoid. Decompose polygons to find the area with help from an experienced mathematics educator in this free video clip.

Transcript

How to decompose polygons to find the area. I'm Bon Crowder and we're talking about taking apart polygons so we can look at their areas. So here we have two polygons. We have a trapezoid that's kind of awkward looking and then we have this other kind of crazy polygon. So when you want to find the area it's like trying to figure out how much carpet you need to put on the floor of a very strange room. Here you can remember the area for the trapezoid but if you don't remember that and you don't have Google on hand really quickly, you can go OK well if I chop off that triangle and chop off that triangle then I have a triangle, a rectangle and a triangle. And if you remember that your area is one half base times height for the two triangles and the area of the rectangle is length times width. Then you can find each area and add them together. For this crazy guy we can do this one of two ways. We can either consider the extra triangle here and then we have the area of the whole rectangle and then the area of the triangle and then subtract or we can look at the area of the rectangle which is this one and then two triangles and then add. So there's a couple of different ways to decompose that one. I'm Bon Crowder and that's how you decompose polygons to find the area.

About the Author

Bon Crowder has taught math to over 15,000 adults in living rooms, classrooms and conferences.