Poinsot's spirals

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In mathematics, Poinsot's spirals are two spirals represented by the polar equations

where csch is the hyperbolic cosecant, and sech is the hyperbolic secant.[1] They are named after the French mathematician Louis Poinsot.

Examples of the two types of Poinsot's spirals[edit]

The Poinsot spiral r=csch(θ/3).
The Poinsot spiral r=sech(θ/3).

See also[edit]


  1. ^ Lawrence, J. Dennis (1972). A Catalog of Special Plane Curves. New York: Dover. pp. 192–194. ISBN 0486602885.