Frustum
Pronunciation: /ˈfrʌs.təm/ Explain
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
 McAdams, David E.. All Math Words Dictionary, frustum. 2nd Classroom edition 201501084799968. pg 83. Life is a Story Problem LLC. January 8, 2015. Buy the book
 Keller, Samuel Smith. Mathematics for Engineering Students, Plane and Solid Geometry. pg 166. www.archive.org. D. Van Nostrand Company. 1908. Last Accessed 7/11/2018. http://www.archive.org/stream/mathengineer00kellrich#page/166/mode/1up/search/apex. Buy the book
 Handbook of Formula and Physical Constants. www.archive.org. Power Engineering Training Systems. Last Accessed 7/11/2018. http://www.archive.org/stream/HandbookOfFormulaAndPhysicalConstants/HandbookOfFormulaeAndConstants#page/n11/mode/1up/search/frustum.
Cite this article as:
McAdams, David E. Frustum. 12/21/2018. All Math Words Encyclopedia. Life is a Story Problem LLC. http://www.allmathwords.org/en/f/frustum.html.
Image Credits
Revision History
12/21/2018: Reviewed and corrected IPA pronunication. (
McAdams, David E.)
7/9/2018: Removed broken links, updated license, implemented new markup, implemented new Geogebra protocol. (
McAdams, David E.)
2/5/2010: Added "References". (
McAdams, David E.)
11/26/2008: Changed equations to images. (
McAdams, David E.)
8/2/2008: Changed equations from images to Hot_Eqn. (
McAdams, David E.)
7/6/2008: Corrected spelling. (
McAdams, David E.)
6/6/2008: Initial version. (
McAdams, David E.)