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## #1 2010-07-30 15:07:56

bossk171
Member
Registered: 2007-07-16
Posts: 305

### catenary

A catenary is the curve:

If you roll a parabola along the x-axis, the focus of the rolling parabola traces out a catenary. I read this a number of places, but I've yet been able to find, or create, a proof.

Last edited by bossk171 (2010-07-30 15:08:18)

There are 10 types of people in the world, those who understand binary, those who don't, and those who can use induction.

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## #2 2010-07-30 16:16:34

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: catenary

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2010-07-30 17:39:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: catenary

Hi;

This page here gives the differential equation for the all the conic sections, yours is on the bottom. The differential equation can used to derive the curve as the focus of the parabola rides on the x axis, it will be found to be a catenary. This derivation is a proof.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #4 2011-07-26 17:39:17

Member
Registered: 2011-07-23
Posts: 16

### Re: catenary

Is the shape of the streamlines formed by a swimming duck a catenary? Is the shape of a supposedly shatterproof (I have broken them) ruler being bent, each end pressed onto my fingertips, a catenary? I know that the shape of a chain held at both ends is a catenary.

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## #5 2011-07-26 21:36:52

anonimnystefy
Real Member
From: Harlan's World
Registered: 2011-05-23
Posts: 16,037

### Re: catenary

Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment
The knowledge of some things as a function of age is a delta function.

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