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Difference between revisions of "Fermat spiral"

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A planar transcendental curve the equation of which in polar coordinates has the form
 
A planar transcendental curve the equation of which in polar coordinates has the form
  
<table class="eq" style="width:100%;"> <tr><td valign="top" style="width:94%;text-align:center;"><img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f038/f038420/f0384201.png" /></td> </tr></table>
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$$\rho=a\sqrt\phi.$$
  
To each value of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f038/f038420/f0384202.png" /> correspond two values of <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f038/f038420/f0384203.png" /> — a positive and a negative one. The Fermat spiral is centrally symmetric relative to the pole, which is a point of inflection. It belongs to the class of so-called algebraic [[Spirals|spirals]].
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To each value of $\phi$ correspond two values of $\rho$ — a positive and a negative one. The Fermat spiral is centrally symmetric relative to the pole, which is a point of inflection. It belongs to the class of so-called algebraic [[Spirals|spirals]].
  
 
They were first studied by P. Fermat (1636).
 
They were first studied by P. Fermat (1636).

Revision as of 11:13, 26 July 2014

A planar transcendental curve the equation of which in polar coordinates has the form

$$\rho=a\sqrt\phi.$$

To each value of $\phi$ correspond two values of $\rho$ — a positive and a negative one. The Fermat spiral is centrally symmetric relative to the pole, which is a point of inflection. It belongs to the class of so-called algebraic spirals.

They were first studied by P. Fermat (1636).

Figure: f038420a

References

[1] A.A. Savelov, "Planar curves" , Moscow (1960) (In Russian)


Comments

References

[a1] J.D. Lawrence, "A catalog of special plane curves" , Dover, reprint (1972)
How to Cite This Entry:
Fermat spiral. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Fermat_spiral&oldid=15613
This article was adapted from an original article by D.D. Sokolov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article