# conic section

## Primary tabs

Defines:
ellipse, parabola, hyperbola, focus, eccentricity, directrix, latus rectum, Dandelin sphere, degenerate conic
Synonym:
conic
Type of Math Object:
Definition
Major Section:
Reference
Groups audience:

## Mathematics Subject Classification

51N20 Euclidean analytic geometry

### Conic, eccentricity, etc.

Hi,
If it were me I would include definitions of
focus
directrix
eccentricity
in the item ConicSection.
Larry

### Re: Conic, eccentricity, etc.

Yes! After all it was very important for Newton!

### Re: Conic, eccentricity, etc.

I made this entry word editable so it can be improved by anyone, I'll make any drawings needed (as soon as I can)
f
G -----> H G
p \ /_ ----- ~ f(G)
\ / f ker f
G/ker f

### Re: Conic, eccentricity, etc.

It is interesting as the conical ones have had important application in the telecommunications and the medicine.

### Re: Conic, eccentricity, etc.

Maybe you should write up an "application" entry on this topic and attach it to the entry on conic sections. I, for one, would be interested to find out about the applications of conic sections to medicine. It sounds plausible since, for instance, the shape of anatomical structures like bones and holes in bones often looks like ellipses and other conic sections. I always thought that conic sections were important for mathematics and physics, but I didn't know that they could be also be good for one's health :)

### Re: Conic, eccentricity, etc.

The ribs in whales are also close approximations
of the cosh curve.

Matte