The surface area of a solid and its volume are different things. It is really important to distinguish them. The surface area is a 2 dimensional area and is the area of the solid’s net, or the area we would need to paint if we wanted to paint it. Let’s think through the example below to get the idea of a solid’s surface area, then see if we can make a formula to describe the surface area of a solid with length l, width w and height h:

Exercise

Let’s complete exercise 17N from page 279 of the textbook:

The answers are below: