ANSWER:
The volume is 16.36 cubic kilometers
Explanation:
We have the formula to calculate the volume of the figure would be:

The height is known to be 2 km, we must calculate the area of the base, which is a triangle and we can calculate it as follows:
![\begin{gathered} A_b=\sqrt[]{s\cdot(s-a)\cdot(s-b)\cdot(s-c)} \\ \text{where s is the semiperimeter } \\ s=(p)/(2) \\ p=4+5+8 \\ p=17 \\ \text{replacing} \\ s=(17)/(2)=8.5 \\ \text{ now, replacing in the area} \\ A_b=√(8.5\cdot\left(8.5-4\right)\cdot\left(8.5-5\right)\cdot\left(8.5-8\right)) \\ A_b=8.18 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/gk59r14rdffo2z0pm9i82xum1dzhk84c0g.png)
Now, replacing in the volume:
