Hello Arthur !
There is a simple and practical way to draw a hyperbola .
I assume that these parameters are known:
2A = the constant difference between the distances of any point of the
hyperbola from the two foci ;
E = the eccentricity of the hyperbola ( >1 ).
1) Draw the two foci : two points whose distance is 2A*E
2) Take a sufficiently long bar or a straightedge and fix one end of this
onto the focus of the other branch of the hyperbola you are going to draw ,
in such a way that the bar is free to rotate around this focus.
3) Connect by a string ( whose lenght is 2A) the other end of the bar to the
other focus (the focus of the branch you are interested in ).
4) Keep the string taut with a pen and run alongside the bar (allow it to
rotate ! )
5) The resulting curve is the desired hyperbola .
I hope this is sufficiently clear ...
This the theory but I've never tried the practice !
Let me know ....
Best regards
Alberto Nicelli
Italy ( 45,5N; 7,8E)
> ----------
> From: Arthur Carlson[SMTP:[EMAIL PROTECTED]
> Sent: martedì 21 aprile 1998 14.02
> To: sundial@rrz.uni-koeln.de
> Subject: latitude with pegs and strings
>
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................................
> In the course of these considerations, I also wished for an easy
> method to construct a hyperbola. You all know how to draw an ellipse
> with a loop of string around two pegs. There is another method to
> make an ellipse involving a stick or string of length "a" with a mark
> at distance "b" from one end. If one end is moved along one axis and
> the mark is moved along the perpendicular axis, then the other end
> traces out an ellipse. I have found a few ways to construct
> hyperbolae that are mathematically correct but not especially
> practical. Is there any way to construct a hyperbola which is of
> similar elegance and practicality to the methods for ellipses? Is
> there an easy way, given a hyperbola, to find its axes, asymptotes, or
> foci?
>
> Thanks for your help.
>
> Art Carlson
>
