Question

Find the surface area of a textbook that is 2 in. × 14 in. × 9 in.
2

in.

×

14


in.

×

9

in.
(1 point)
Responses

172 in.2
172

in.
2
172 in. squared

50 in.2
50

in.
2
50 in. squared

252 in.2
252

in.
2
252 in. squared

344 in.2

Answer 1

To find the surface area of a rectangular prism (like a textbook), we use the formula:

\[
\text{Surface Area} = 2(lw + lh + wh)
\]

where \( l \) is the length, \( w \) is the width, and \( h \) is the height. In this case, we have the dimensions:

- \( l = 14 \) inches
- \( w = 2 \) inches
- \( h = 9 \) inches

Now, plug these values into the formula:

1. Calculate the products:
- \( lw = 14 \times 2 = 28 \)
- \( lh = 14 \times 9 = 126 \)
- \( wh = 2 \times 9 = 18 \)

2. Now sum these products:
- \( lw + lh + wh = 28 + 126 + 18 = 172 \)

3. Now, multiply by 2 to find the surface area:
- \(\text{Surface Area} = 2 \times 172 = 344\) square inches

Thus, the surface area of the textbook is \( \boxed{344 \, \text{in.}^2} \).