# conjugate diameters of ellipse

## Primary tabs

Defines:
diameter of ellipse, conjugate diameter, conjugate radii
Keywords:
diameter, tangent of ellipse
Type of Math Object:
Topic
Major Section:
Reference
Parent:
Groups audience:

## Mathematics Subject Classification

### Isn't It Conjugate vs. Transverse?

Given the two principal axes, x and y, isn't it just the
north-south y-axis is the conjugate axis, while the east-west, *perpendicular* x-axis is the transverse axis? See

~Kaimbridge~

### Re: Isn't It Conjugate vs. Transverse?

The transverse axis and the conjugate axis concern only the hyperbola; the former is the line segment connecting the vertices. See http://planetmath/encyclopedia/Hyperbola.html.
Jussi

### Re: Isn't It Conjugate vs. Transverse?

The transverse axis and the conjugate axis concern only the hyperbola; the former is the line segment connecting the vertices. See http://planetmath.org/encyclopedia/Hyperbola.html. (I corrected the URL.)
Jussi

### Re: Isn't It Conjugate vs. Transverse?

Excuse, the following is the _correct_ URL:
http://planetmath/encyclopedia/Hyperbola2.html.
Jussi

### Re: Isn't It Conjugate vs. Transverse?

Oh excuse still, it is

### Re: Isn't It Conjugate vs. Transverse?

But what about the sources I noted? They both are talking about ellipses, not hyperbolae *AND* when talking about great circle delineation, you are dealing with a transverse graticule (i.e, the polar vertex is "pulled down" to the equator). See

~Kaimbridge~

### Re: Isn't It Conjugate vs. Transverse?

Dear Kaimbridge,
Maybe on your speciality (geodesy?), those terms are as you say. In mathematics, we speak only of the transverse axis and the conjugate axis of a hyperbola; see also in Wiki
http://en.wikipedia.org/wiki/Conjugate_axis.
Wolfram (http://mathworld.wolfram.com/) doesn't know tose terms.
Best regards,
Jussi

### Re: Isn't It Conjugate vs. Transverse?

P. S. -- As for ellipse, one speaks of major and minor (semi)axes.