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?

A. 162 in.^2
B. 18 in.^2
C. 1,458 in.^2
D. 54 in.^2

1 answer

When a three-dimensional shape, such as a triangular prism, is dilated by a scale factor \( k \), the surface area of the shape is affected by the square of that scale factor.

The relationship for the surface area after dilation can be calculated with the following formula:

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

Given:

  • Original Surface Area = 486 in²
  • Scale Factor \( k = \frac{1}{3} \)

Now, calculate \( k^2 \):

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

Now, substitute the values into the new surface area formula:

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

To perform the multiplication:

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

Thus, the new surface area after the dilation is:

\[ \boxed{54 , \text{in}^2} \]