Also known as araneidan, this curve owes its name to its spider-like shape. It is given by the polar equation
where 
and 
is an integer (right figure). An alternate version of
the araneidan has the slightly different polar equation
where 
and 
is an integer (left figure).
This entry contributed by Margherita
Barile
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References
Shikin, E. V. Handbook and Atlas of Curves. Boca Raton, FL: CRC Press, pp. 76-78, 1995.Referenced
on Wolfram|Alpha
Arachnida
Cite this as:
Barile, Margherita. "Arachnida." From MathWorld--A Wolfram Web Resource, created by Eric
W. Weisstein. https://mathworld.wolfram.com/Arachnida.html
Subject classifications
![r=a(sin(ntheta))/(sin[(n-1)theta]),](/images/equations/Arachnida/NumberedEquation1.svg)
![r=a(sin(ntheta))/(sin[(n+1)theta]),](/images/equations/Arachnida/NumberedEquation2.svg)
