check the picture below.
notice the triangular faces are really just an equilateral triangle.
and the volume of the triangular prism is just the area of the triangular face times the length of 25.
[tex]\bf \textit{area of an equilateral triangle}\\\\
A=\cfrac{s^2\sqrt{3}}{4}~~
\begin{cases}
s=length~of\\
\qquad a~side\\
------\\
s=14
\end{cases}\implies A=\cfrac{14^2\sqrt{3}}{4}\implies A=49\sqrt{3}[/tex]
therefore, the area of the prism is just A * 25.
