Pentagonon^[1] (Graece πεντάγωνον < πεντα- 'quinque' + γωνία 'angulus'), etiam 5-gon appellatum, in geometria est polygonon quinque angulorum vel laterum. Summa angulorum internorum in pentagono simplice est 540°.

Exempla pentagonorum

Plantae

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  Transversa Abelmoschi esculenti sectio.
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  Convolvulaceis, sicut multis floribus aliis, est forma pentagonalis.
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  Gynoecium mali quinque carpella continet, in stella quinquies punctata ordinata.
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  Fructui Averrhoae carambolae est symmetria quincuplex.

Animalia

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  Oreaster reticulatus. Multis echinodermatibus est symmetria quincuplex radialis.
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  Aliud echinodermatis exemplum: endosceletus echinoidei.
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  Adumbratio echinodermatis classis Ophiuroideorum.

Mineralia

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  Quasicrystallum Ho-Mg-Zn, ut dodecahedron pentagonale formatum Facies sunt vera pentagona regularia.
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  Crystallum pyritohedrale pyritis. Pyritohedrono est duodecim eaedem facies pentagonales, quae autem regulares non necesse sunt.

Res artificiosae

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  Pentagonon, praetorium United States Department of Defense.
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  Lamina domestica agri basipilae.

Pentagona in polyhedra

Ih	Th	Td	O	I	D5d
Dodecahedron	Pyritohedron	Tetartoidum	Icositetrahedron pentagonale	Hexecontahedron pentagonale	Trapezohedron truncatum

Notae

Bibliographia

• Buchholz, Ralph H., et James A. MacDougall. 2008. "Cyclic polygons with rational sides and area." Journal of Number Theory 128 (1): 17–48. doi:10.1016/j.jnt.2007.05.005. MR 2382768. Editio interretialis.
• Conway, John H., Heidi Burgiel, et Chaim Goodman-Strauss. 2008. "Generalized Schaefli symbols: Types of symmetry of a polygon." In The Symmetries of Things, capitulum 20, 275–78. ISBN 978-1-56881-220-5.
• Meskhishvili, Mamuka. 2020. "Cyclic Averages of Regular Polygons and Platonic Solids." Communications in Mathematics and Applications 11: 335–55. Editio interretialis.
• Robbins, D. P. 1994. "Areas of Polygons Inscribed in a Circle." Discrete and Computational Geometry 12: 223–36. doi:10.1007/bf02574377.