Epispiral

An epispiral with equation r(θ)=2sec(2θ)

The epispiral is a plane curve with polar equation

${\displaystyle \ r=a\sec {n\theta }}$.

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.

See also[]

• Logarithmic spiral
• Rose (mathematics)

References[]

• J. Dennis Lawrence (1972). A catalog of special plane curves. Dover Publications. p. 192. ISBN 0-486-60288-5.
• https://www.mathcurve.com/courbes2d.gb/epi/epi.shtml

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