prismoidal formula

prismoidal formula

[priz¦mȯid·əl ′fȯr·myə·lə]
(mathematics)
A formula that gives the volume of a prismatoid as (1/6) h (A1+ 4 Am + A2), where h is the altitude, A1 and A2 are the areas of the bases, and Am is the area of a plane section halfway between the bases.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.