in plain and short, to get the volume of a triangular prism, we simply get the area of the triangular face and multiply that by the length.
in this case hmmm let's see the triangle has sides of 12, 12 and ... well, 12 again, is an equilateral triangle, so we get that area and multiply it by 17,
[tex]\bf \textit{area of an equilateral triangle}\\\\ A=\cfrac{s^2\sqrt{3}}{4}~~ \begin{cases} s=side's\\ \qquad length\\ \cline{1-1} s = 12 \end{cases}\implies A=\cfrac{12^2\sqrt{3}}{4}\implies A=36\sqrt{3} \\\\[-0.35em] ~\dotfill\\\\ ~\hfill \stackrel{\textit{volume of the triangular prism}}{(36\sqrt{3})(17)\approx 1060.02}~\hfill[/tex]
