Epispiral

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An epispiral with equation r(th)=2sec(2th) Epispiral.svg
An epispiral with equation r(θ)=2sec(2θ)

The epispiral is a plane curve with polar equation

.

There are n sections if n is odd and 2n if n is even.

It is the polar or circle inversion of the rose curve.

In astronomy the epispiral is related to the equations that explain planets' orbits.

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