Formula for frustum of pyramid:
[tex]V = \frac{h}{3} (A _{1} + A _{2} + \sqrt{A _{1}A _{2} ) [/tex]
where:
h = also altitude, the perpendicular distance between A1 (lower base) and
A2 (upper base)
[tex] A_{1} = lower base[/tex]
[tex] A_{2} = upper base[/tex]