In mathematics, Poinsot's spirals are two spirals represented by the polar equations
r = a csch ( n θ ) {\displaystyle r=a\ \operatorname {csch} (n\theta )}
r = a sech ( n θ ) {\displaystyle r=a\ \operatorname {sech} (n\theta )}
where csch is the hyperbolic cosecant, and sech is the hyperbolic secant. They are named after the French mathematician Louis Poinsot.
Examples of the two types of Poinsot's spirals
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