CK-12 Geometry-Concepts

http://www.ck12.org Chapter 11. Surface Area and Volume

Using the net, we have:

SAprism= 2 ( 4 )( 10 )+ 2 ( 10 )( 17 )+ 2 ( 17 )( 4 )

= 80 + 340 + 136

= 556 cm^2

Because this is still area, the units are squared.

Example B

Find the surface area of the prism below.

This is a right triangular prism. To find the surface area, we need to find the length of the hypotenuse of the base
because it is the width of one of the lateral faces. Using the Pythagorean Theorem, the hypotenuse is

72 + 242 =c^2

49 + 576 =c^2

625 =c^2

c= 25

Looking at the net, the surface area is:

SA= 28 ( 7 )+ 28 ( 24 )+ 28 ( 25 )+ 2

(

1

2

· 7 · 24

)

SA= 196 + 672 + 700 + 168 = 1736