Prism

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Prism1Prism2

A general prism is a polyhedron possessing two congruent polygonal faces and with all remaining faces parallelograms (Kern and Bland 1948, p. 28; left figure).

A right prism is a prism in which the top and bottom polygons lie on top of each other so that the vertical polygons connecting their sides are not only parallelograms, but rectangles (right figure). A prism that is not a right prism is known as an oblique prism. If, in addition, the upper and lower bases are rectangles, then the prism is known as a cuboid.

PrismNets

The regular right prisms have particularly simple nets, given by two oppositely-oriented n-gonal bases connected by a ribbon of n squares. The graph corresponding to the skeleton of a prism is known, not surprisingly, as a prism graph.

The volume of a prism of height h and base area A is simply

 V=Ah.
(1)
Prism03Prism04Prism05Prism06
Prism07Prism08Prism09Prism10

The above figure shows the first few regular right prisms, whose faces are regular n-gons. The 4-prism with unit edge lengths is simply the cube. The dual polyhedron of a regular right prism is a dipyramid.

A regular right unit n-prism has surface area

S_n=2A_n+n·1^2
(2)
=n[1+1/2cot(pi/n)],
(3)

where A_n is the area of the corresponding regular polygon. The first few surface areas are

S_3=1/2(6+sqrt(3))
(4)
S_4=6
(5)
S_5=5+1/2sqrt(5(5+2sqrt(5)))
(6)
S_6=3(2+sqrt(3))
(7)
S_7=(64x^6-2688x^5+43120x^4-329280x^3+1181292x^2-1479016x-487403)_6
(8)
S_8=4(3+sqrt(2))
(9)
S_9=(64x^6-3456x^5+66096x^4-513216x^3+918540x^2+6141096x-19309023)_6
(10)
S_(10)=5(2+sqrt(5+2sqrt(5))).
(11)

The algebraic degrees of these areas for n=3, 4, ... are 2, 1, 4, 2, 6, 2, 6, 4, 10, 2, 12, 6, 8, 4, 16, 6, 18, 4, ... (OEIS A089929).

A regular right unit n-prism has volume

 V_n=1·A_n=1/4ncot(pi/n).
(12)

The first few volumes are

V_3=1/4sqrt(3)
(13)
V_4=1
(14)
V_5=1/4sqrt(5(5+2sqrt(5)))
(15)
V_6=3/2sqrt(3)
(16)
V_7=(4096x^6-62720x^4+115248x^2-16807)_6
(17)
V_8=2(1+sqrt(2))
(18)
V_9=(4096x^6-186624x^4+1154736x^2-177147)_6
(19)
V_(10)=5/2sqrt(5+2sqrt(5)).
(20)

The algebraic degrees of the volumes are the same as for the surface areas.

The right regular triangular prism, square prism (cube), and hexagonal prism are all space-filling polyhedra.

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