Frustum
Pronunciation: /ˈfrʌs təm/ ?
A frustum is the part of a solid between two
parallel planes.^{[1]} Most often, frustum refers to a truncated cone or pyramid. The word
frustum is often misspelled frustrum.
A frustum based on a
cone
is called a conical frustum. A frustum based on a pyramid
is called a pyramidal frustum.

Right Conical Frustum 
 Figure 1: Conical Frustum 

Formulas for a right conical frustum:
R_{1} is the radius of the smaller circle.
R_{2} is the radius of the larger circle.
h is the height at the axis.
s is the slant height.
A is the surface area of the sides, not including the base and top.
V is the volume.

Right Pyramidal Frustum 
 Figure 1: Pyramidal Frustum 

Formulas for a right pyramidal frustum:
p_{1} is the perimeter of the base.
p_{2} is the perimeter of the top.
h is the height.
s is the slant height.
A_{1} is the area of the base.
A_{2} is the area of the top.
S is the surface area not including the base or top.
V is the volume.

References
 frustum. http://wordnet.princeton.edu/. WordNet. Princeton University. (Accessed: 20110108). http://wordnetweb.princeton.edu/perl/webwn?s=frustum&sub=Search+WordNet&o2=&o0=1&o7=&o5=&o1=1&o6=&o4=&o3=&h=.
 Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry, pg 166. D. Van Nostrand Company, 1908. (Accessed: 20100102). http://www.archive.org/stream/mathengineer00kellrich#page/166/mode/1up/search/apex.
 Handbook of Formula and Physical Constants. Power Engineering Training Systems. (Accessed: 20100205). http://www.archive.org/stream/HandbookOfFormulaAndPhysicalConstants/HandbookOfFormulaeAndConstants#page/n11/mode/1up/search/frustum.
Cite this article as:
Frustum. 20091231. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/f/frustum.html.
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20100205: Added "References" (
McAdams, David.)
20081126: Changed equations to images (
McAdams, David.)
20080802: Changed equations from images to Hot_Eqn (
McAdams, David.)
20080706: Corrected spelling (
McAdams, David.)
20080606: Initial version (
McAdams, David.)