The prismatoid theorem states that the volume of a prismatoid is equal to the sum of the volumes of a pyramid, a wedge, and a parallelepiped.
For proof and details of the decomposition, see Kern and Bland (1948, pp. 121-130).
The term "prismatoid theorem" in this context should not be confused with
the prismatoid formula.
Kern, W. F. and Bland, J. R. "Prismatoid Theorem," "Proof of the Prismoidal Formula," and "Application
of Prismatoid Theorem." §43-45 in Solid
Mensuration with Proofs, 2nd ed. New York: Wiley, pp. 121-130, 1948.
