Frustum
In geometry, a frustum (Latin for 'morsel'); (pl.: frusta or frustums) is the portion of a solid (normally a pyramid or a cone) that lies between two parallel planes cutting the solid. In the case of a pyramid, the base faces are polygonal and the side faces are trapezoidal. A right frustum is a right pyramid or a right cone truncated perpendicularly to its axis; otherwise, it is an oblique frustum. In a truncated cone or truncated pyramid, the truncation plane is not necessarily parallel to the cone's base, as in a frustum. If all its edges are forced to become of the same length, then a frustum becomes a prism (possibly oblique or/and with irregular bases).
| Set of pyramidal right n-gonal frustums | |
|---|---|
Examples: right pentagonal and square frustums (n = 5 and n = 4) | |
| Faces | n isosceles trapezoids, 2 regular n-gons |
| Edges | 3n |
| Vertices | 2n |
| Symmetry group | Cnv, [1,n], (*nn) |
| Dual polyhedron | asymmetric bipyramid |
| Properties | convex |
| Net | |
| Example: net of right trigonal frustum (n = 3) | |
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