Talk:Conjugate diameters

Diagram request

The hyperbola diagram in this article has no example of conjugate diameters besides those corresponding to the axes. A diagram is requested to show a sample conjugate pair of diameters of a hyperbola. Current image caption specifies these diameters with (x,y) coordinates.Rgdboer (talk) 22:49, 16 March 2011 (UTC)

And I would like to see a counterexample for the circle. ᛭ LokiClock (talk) 18:25, 20 June 2011 (UTC)

Diagrams for conjugate diameters are now in place.Rgdboer (talk) 20:06, 12 April 2014 (UTC)

Lorentz transformations

The following text was removed today:

Events separated by space-like intervals cannot by a Lorentz transformation occur at the same location; time-like separations cannot be transformed to occur at the same time.

This article refers only to a version of the Principle of relativity; details of Lorentz transformations are found in that article.Rgdboer (talk) 20:06, 12 April 2014 (UTC)

For ellipse

Can someone add this to the wiki with a suitable diagram?

Let the slopes of 2 conjugate diameters (passing through origin) be m1 and m2. Let one parallel chord with slope m2 cut the ellipse at (acosθ, bsinθ) and (acosφ, bsinφ), and have its midpoint (h, k).

So the slope

$m_{2}={\dfrac {b\sin \theta -b\sin \phi }{a\cos \theta -a\cos \phi }}={\dfrac {-b}{a\tan({\frac {\theta +\phi }{2}})}}$

From midpoint formula,

$(h,k)=({\frac {a}{2}}(\cos \theta +\cos \phi ),{\frac {b}{2}}(\sin \theta +\sin \phi ))$

Since the parallel chord is bisected by the other conjugate diameter, point (h,k) must lie on it:

$m_{1}={\dfrac {k}{h}}={\dfrac {b\tan({\frac {\theta +\phi }{2}})}{a}}$

$m_{1}m_{2}={\dfrac {-b^{2}}{a^{2}}}$

Shubjt (talk) 07:07, 3 January 2022 (UTC)

Your formula is contained in the article Ellipse#parameters#tangent:

If $(x_{1},y_{1})$ and $(u,v)$ are two points of the ellipse such that ${\textstyle {\frac {x_{1}u}{a^{2}}}+{\tfrac {y_{1}v}{b^{2}}}=0}$, then the points lie on two conjugate diameters.

--Ag2gaeh (talk) 16:18, 3 January 2022 (UTC)