Find the surface area of a textbook that is

2 in. × 14 in. × 9 in. (1 point)
252 in.
2
172 in.
2
50 in.
2
344 in.
2

1 answer

To find the surface area of a rectangular prism (which is the shape of the textbook in this case), we can use the formula:

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

where:

  • \( l \) is the length,
  • \( w \) is the width,
  • \( h \) is the height.

In this case, the dimensions of the textbook are:

  • \( l = 2 \) inches,
  • \( w = 14 \) inches,
  • \( h = 9 \) inches.

Now let's calculate each part:

  1. Calculate \( lw \): \[ lw = 2 \times 14 = 28 , \text{in}^2 \]

  2. Calculate \( lh \): \[ lh = 2 \times 9 = 18 , \text{in}^2 \]

  3. Calculate \( wh \): \[ wh = 14 \times 9 = 126 , \text{in}^2 \]

Now, substitute these values back into the surface area formula:

\[ \text{Surface Area} = 2(28 + 18 + 126) \]

First, add the values inside the parentheses:

\[ 28 + 18 + 126 = 172 \]

Now substitute back into the formula:

\[ \text{Surface Area} = 2 \times 172 = 344 , \text{in}^2 \]

Thus, the surface area of the textbook is:

\[ \boxed{344 , \text{in}^2} \]