perpendicular axis theorem
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perpendicular axis theorem[¦pər·pən¦dik·yə·lər ′ak·səs ‚thir·əm]
A theorem which states that the sum of the moments of inertia of a plane lamina about any two perpendicular axes in the plane of the lamina is equal to the moment of inertia about an axis through their intersection perpendicular to the lamina.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.