Hi Yadgar,


47091c9b$1@news.povray.org...
> High!
>
> Xavier M. schrieb:
>
>> The equation of your ellipsoid is:
>> (x/0.115)^2 + (y/0.108)^2 + (z/0.138)^2 - 1 = 0
>> The cut surface z==-0.097 is an ellipse, with equation:
>> (x/0.115)^2 + (y/0.108)^2 + (0.097 /0.138)^2 - 1 = 0
>> the width at y=0 is given by:
>> (x/0.115)^2 + (0.097 /0.138)^2 - 1 = 0
>> <=> |x| = 0.115 * sqrt ( 1 - (0.097 /0.138)^2)
>> so width = 2 * 0.115 * sqrt ( 1 - (0.097 /0.138)^2)
>
> Meanwhile, I found out a different solution:
> as the length of the secant of a circle or ellipse decreases with 
> increasing distance to its center point proportionally with the cosine of 
> the arcus-sine of distance/radius, the searched length here is 
> 0.115*2*cos(asin(0.097/0.138)) = 0.163596726 !

a little more complicated formula, but the same result, since 
(cos(asin(x)))^2= 1-x^2

> See you in Khyberspace!

By the way what is Khyberspace? The page on your web site has been "under 
construction" for a long time now...

Xavier

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