
Hyperbolic spiral for a = 2
A hyperbolic spiral is a flat transcendental curve . The hyperbolic spiral equation in the polar coordinate system is the inverse of the Archimedean spiral equation and is written as follows:
- {\ displaystyle \ rho \ phi = a}

The equation of the hyperbolic spiral in Cartesian coordinates:
- {\ displaystyle x = \ rho \ cos \ phi, \ qquad y = \ rho \ sin \ phi,}

Parametric notation of the equation:
- {\ displaystyle x = a {\ cos t \ over t}, \ qquad y = a {\ sin t \ over t},}

The spiral has the asymptote y = a : for t, the ordinate tends to zero, tends to a , and the abscissa goes to infinity:
- {\ displaystyle \ lim _ {t \ to 0} x = a \ lim _ {t \ to 0} {\ cos t \ over t} = \ infty,}

- {\ displaystyle \ lim _ {t \ to 0} y = a \ lim _ {t \ to 0} {\ sin t \ over t} = a \ cdot 1 = a.}
