hello
to solve this problem, we have to know the formula of volume of a triangular pyramid.
[tex]\begin{gathered} v=\frac{1}{3}\times B\times h \\ v=\text{volume} \\ B=\text{base area} \\ h=\text{height} \end{gathered}[/tex][tex]\begin{gathered} B=\text{area of a square} \\ B=l\times l \\ l=142 \\ b=142\times142 \\ b=20164ft^2 \end{gathered}[/tex]now we can multiply the base area with the height to know the volume
[tex]\begin{gathered} v=\frac{1}{3}b\times h \\ b=20164ft^2 \\ h=861ft \\ v=\frac{1}{3}\times20164\times861 \\ v=5787068ft^3 \end{gathered}[/tex]the volume of the pyramid is 5787068 feet cubed
