To find the new volume of a triangular prism after dilation by a linear scale factor \( k \), we start with the relationship between volume and scale factor.
When a 3-dimensional figure is dilated by a scale factor \( k \), the new volume \( V' \) is given by the formula:
\[ V' = k^3 \times V \]
where \( V \) is the original volume. In your case:
- The original volume \( V = 42 \)
- The linear scale factor \( k = 3 \)
Now, we can calculate the new volume:
\[ V' = 3^3 \times 42 \]
Calculating \( 3^3 \):
\[ 3^3 = 27 \]
Now, substituting this back into the equation for the new volume:
\[ V' = 27 \times 42 \]
Now we perform the multiplication:
\[ V' = 1134 \]
Thus, the new volume of the triangular prism after dilation is:
\[ \boxed{1134} \]