Fermat's Spiral
An Archimedean Spiral with 
having polar equation
discussed by Fermat
in 1636 (MacTutor Archive). It is also known as the Parabolic Spiral. For any givenPositive value of 
, there are two corresponding values of 
of opposite signs. The resulting spiral istherefore symmetrical about the origin. The Curvature is
References
Dixon, R. Mathographics. New York: Dover, p. 121, 1991. Gray, A. Modern Differential Geometry of Curves and Surfaces. Boca Raton, FL: CRC Press, pp. 69-70, 1993. Lee, X. ``Equiangular Spiral.''http://www.best.com/~xah/SpecialPlaneCurves_dir/EquiangularSpiral_dir/equiangularSpiral.html. Lockwood, E. H. A Book of Curves. Cambridge, England: Cambridge University Press, p. 175, 1967. MacTutor History of Mathematics Archive. ``Fermat's Spiral.''http://www-groups.dcs.st-and.ac.uk/~history/Curves/Fermats.html. Wells, D. The Penguin Dictionary of Curious and Interesting Geometry. Middlesex, England: Penguin Books, 1991.
- Radius Vector
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- Radon-Nikodym Theorem
- Radon Transform
- Radon Transform--Cylinder
- Radon Transform--Delta Function
- Radon Transform--Gaussian
- Radon Transform--Square
- Rado's Sigma Function
- Railroad Track Problem
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- Ramanujan Constant
- Ramanujan Continued Fraction
- Ramanujan Cos/Cosh Identity
- Ramanujan-Eisenstein Series
- Ramanujan Function
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- Ramanujan-Petersson Conjecture
- Ramanujan Psi Sum
- Ramanujan's Hypergeometric Identity
- Ramanujan's Hypothesis
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