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Difference between revisions of "Cycloidal curve"

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The plane curve described by a point that is connected to a circle rolling along another circle.
 
The plane curve described by a point that is connected to a circle rolling along another circle.
  
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The parametric equation of a cycloidal curve can be written in complex form:
 
The parametric equation of a cycloidal curve can be written in complex 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/c/c027/c027550/c0275501.png" /></td> </tr></table>
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$$z=l_1e^{\omega_1ti}+l_2e^{\omega_2ti},\quad z=x+iy.$$
  
 
This is a special case of an equation
 
This is a special case of an equation
  
<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/c/c027/c027550/c0275502.png" /></td> </tr></table>
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$$z=l_0+l_1e^{\omega_1t_i}+\dotsb+l_ne^{\omega_nti},$$
  
 
which describes cycloids of higher order.
 
which describes cycloids of higher order.
  
 
====References====
 
====References====
<table><TR><TD valign="top">[1]</TD> <TD valign="top">  A.A. Savelov,  "Planar curves" , Moscow  (1960)  (In Russian)</TD></TR></table>
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<table>
 
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<TR><TD valign="top">[1]</TD> <TD valign="top">  A.A. Savelov,  "Planar curves" , Moscow  (1960)  (In Russian)</TD></TR>
 
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<TR><TD valign="top">[a1]</TD> <TD valign="top">  J.D. Lawrence,  "A catalog of special plane curves" , Dover, reprint  (1972)</TD></TR>
 
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<TR><TD valign="top">[a2]</TD> <TD valign="top">  K. Fladt,  "Analytische Geometrie spezieller ebener Kurven" , Akad. Verlagsgesell.  (1962)</TD></TR></table>
====Comments====
 
 
 
 
 
====References====
 
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  J.D. Lawrence,  "A catalog of special plane curves" , Dover, reprint  (1972)</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  K. Fladt,  "Analytische Geometrie spezieller ebener Kurven" , Akad. Verlagsgesell.  (1962)</TD></TR></table>
 

Latest revision as of 16:53, 8 April 2023

The plane curve described by a point that is connected to a circle rolling along another circle.

If the generating point lies on the circle, then the cycloidal curve is called an epicycloid or a hypocycloid, depending on whether the rolling circle is situated outside or inside the fixed circle. If the point is situated outside or inside the rolling circle then the cycloidal curve is called a trochoid.

The form of a cycloidal curve depends on the ratio between the radii of the circles. E.g., if the ratio of the radii is rational, then the cycloidal curve is a closed algebraic curve, but if the ratio is irrational, then the cycloidal curve is not closed. Among the epicycloids the best known is the cardioid, among the hypocycloids — the astroid and the Steiner curve.

The parametric equation of a cycloidal curve can be written in complex form:

$$z=l_1e^{\omega_1ti}+l_2e^{\omega_2ti},\quad z=x+iy.$$

This is a special case of an equation

$$z=l_0+l_1e^{\omega_1t_i}+\dotsb+l_ne^{\omega_nti},$$

which describes cycloids of higher order.

References

[1] A.A. Savelov, "Planar curves" , Moscow (1960) (In Russian)
[a1] J.D. Lawrence, "A catalog of special plane curves" , Dover, reprint (1972)
[a2] K. Fladt, "Analytische Geometrie spezieller ebener Kurven" , Akad. Verlagsgesell. (1962)
How to Cite This Entry:
Cycloidal curve. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Cycloidal_curve&oldid=18501
This article was adapted from an original article by D.D. Sokolov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article