Poinsot's spirals
# Poinsot's spirals

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

    $r=a\ \operatorname {csch} (n\theta )$
    $r=a\ \operatorname {sech} (n\theta )$

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

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