A triangular prism has a surface area of 486 in^2. If it were dilated using a scale factor of 1/3, what would the new surface area be?

162 in.^2
18 in.^2
54 in.^2
1,458 in.^2

1 answer

To find the new surface area of a triangular prism after dilation by a scale factor, we need to remember how surface area changes with scale factors.

When an object is dilated using a scale factor of \( k \), the new surface area is calculated by multiplying the original surface area by \( k^2 \) (since surface area is a two-dimensional measurement).

Given:

  • Original surface area = 486 in²
  • Scale factor \( k = \frac{1}{3} \)

We calculate the new surface area:

\[ \text{New Surface Area} = \text{Original Surface Area} \times k^2 \]

Calculating \( k^2 \):

\[ k^2 = \left(\frac{1}{3}\right)^2 = \frac{1}{9} \]

Now, we calculate the new surface area:

\[ \text{New Surface Area} = 486 \times \frac{1}{9} \]

\[ \text{New Surface Area} = \frac{486}{9} = 54 \text{ in}^2 \]

Thus, the new surface area after dilation with a scale factor of \( \frac{1}{3} \) would be 54 in².