Step 1: Identify the base, height and length of the triangular prism from the given diagram.
[tex]base=2 \; m\\height=1.5 \; m\\length=3 \; m[/tex]
Step 2: Substitute the base, height and length values in the formula given in the diagram.
[tex]Volume(V)=\frac{base\times height}{2}\times length\\\\V=\frac{2\times 1.5}{2}\times 3\\\\V=4.5m^3[/tex]
Conclusion:
The volume of sand needed to fill on is 4.5 cubic meters