Example 3
Figure 2
The surface area is the sum of the areas of the faces. To find the areas of the
faces, you need to figure out what kinds of polygons they are so that you’ll
know what formulas to use. Start with the bases, which are said to be
“triangles with sides of lengths 3, 4, and 5.” If these side lengths don’t ring a
bell in your head, then you’d better go back to chapter 5 and bone up on
your special triangles. This is a 3-4-5 triangle, which means that it’s a right
In Figure 2, the bases of the right uniform solid are triangles with sides
of lengths 3, 4, and 5. If the volume of the solid is 30, what is the total
surface area?