Find the surface area of the following rectangular prism.
Surface area is adding the area of all of the faces together. But instead of adding them one by one, they actually kind of come in pairs. There are two of these and they are both 11 by nine feet. And the area of a rectangle is length times width. So we need to take 11 times nine. But like we said, there are two of them. so we need to multiply by two and now we will add the next pair.
Here, we have the two pink rectangles. They are nine by 18 feet. So we take two times nine times 18. And our last pair will be the top and bottom and they are 11 by 18 feet. So we have two times 11 times 18. So we have two times 99 plus two times 162 plus two times 198, which equals 198 plus 324 plus 396, which equals 918 feet square since this is an area.