# Cochleoid

${\displaystyle r={\frac {\sin \theta }{\theta }},-20<\theta <20}$

A cochleoid is a snail-shaped curve similar to a strophoid which can be represented by the polar equation

${\displaystyle r={\frac {a\sin \theta }{\theta }}}$
${\displaystyle (x^{2}+y^{2})\arctan {\frac {y}{x}}=ay}$

or the parametric equations

${\displaystyle x={\frac {a\sin t\cos t}{t}}}$, ${\displaystyle y={\frac {a\sin ^{2}t}{t}}}$ .

## References

• J. Dennis Lawrence (1972). A catalog of special plane curves. Dover Publications. p. 192. ISBN 0-486-60288-5.