Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > sci.math > #430877 > unrolled thread
| Started by | Archimedes Plutonium <plutonium.archimedes@gmail.com> |
|---|---|
| First post | 2019-01-05 07:19 -0800 |
| Last post | 2019-01-06 21:47 -0800 |
| Articles | 4 on this page of 24 — 6 participants |
Back to article view | Back to sci.math
AP's thoughts as of 5JAN2019// three proofs that ellipse is never a conic Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 07:19 -0800
Legitimate geometry question on cone-plane intersection moroney@world.std.spaamtrap.com (Michael Moroney) - 2019-01-05 17:48 +0000
Re: Legitimate geometry question on cone-plane intersection Alan Mackenzie <acm@muc.de> - 2019-01-05 18:58 +0000
Re: Legitimate geometry question on cone-plane intersection moroney@world.std.spaamtrap.com (Michael Moroney) - 2019-01-05 19:44 +0000
Re: Legitimate geometry question on cone-plane intersection Peter Percival <peterxpercival@hotmail.com> - 2019-01-05 20:15 +0000
Re: Legitimate geometry question on cone-plane intersection Alan Mackenzie <acm@muc.de> - 2019-01-07 03:15 +0000
Re: Legitimate geometry question on cone-plane intersection moroney@world.std.spaamtrap.com (Michael Moroney) - 2019-01-07 04:44 +0000
Re: Legitimate geometry question on cone-plane intersection Peter Percival <peterxpercival@hotmail.com> - 2019-01-05 20:13 +0000
My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 13:44 -0800
try wrapping a ellipse in a cone wrapper Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 14:24 -0800
Re: try wrapping a ellipse in a cone wrapper Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 14:40 -0800
researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 17:37 -0800
researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 21:13 -0800
Re: Archimedes "Village Idiot" Plutonium flunked the Math Test of a lifetime-generation test moroney@world.std.spaamtrap.com (Michael Moroney) - 2019-01-06 05:55 +0000
not even a constant percentage in the rectangles Re: researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 21:59 -0800
no percentage formula Re: researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 22:14 -0800
not even rectangles Re: no percentage formula Re: researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 23:02 -0800
directrix Re: not even rectangles Re: no percentage formula Re: researching if the ellipse has an internal universal constant of 1/137 Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 23:34 -0800
understanding the Ellipse well,is the same as understanding angular momentum of physics well Archimedes Plutonium <plutonium.archimedes@gmail.com> - 2019-01-05 23:51 -0800
Re: understanding the Ellipse well,is the same as understanding angular momentum of physics well Me <franz.fritschee.ff@gmail.com> - 2019-01-06 03:10 -0800
Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse Me <franz.fritschee.ff@gmail.com> - 2019-01-06 03:08 -0800
Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse Alan Mackenzie <acm@muc.de> - 2019-01-06 11:17 +0000
Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse moroney@world.std.spaamtrap.com (Michael Moroney) - 2019-01-06 18:42 +0000
Re: AP's thoughts as of 5JAN2019// three proofs that ellipse is never a conic Jan <filmart@gmail.com> - 2019-01-06 21:47 -0800
Page 2 of 2 — ← Prev page 1 [2]
| From | Me <franz.fritschee.ff@gmail.com> |
|---|---|
| Date | 2019-01-06 03:08 -0800 |
| Subject | Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse |
| Message-ID | <218d144d-96ca-475d-a437-66ec835c34e7@googlegroups.com> |
| In reply to | #430890 |
On Saturday, January 5, 2019 at 10:44:55 PM UTC+1, Archimedes Plutonium wrote: > Notice that [...] you can fit the ellipse inside the cylinder and make a cut > to get the ellipse Right. Same with ellipses and cones. > But notice as you elongate a cone, you always have a sharp tip top and a > flaring-out at the bottom. Right. > In other words, no ellipse comes out of a cone. Nope. Non sequitur.
[toc] | [prev] | [next] | [standalone]
| From | Alan Mackenzie <acm@muc.de> |
|---|---|
| Date | 2019-01-06 11:17 +0000 |
| Subject | Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse |
| Message-ID | <q0so3g$1oih$1@news.muc.de> |
| In reply to | #430890 |
Archimedes Plutonium <plutonium.archimedes@gmail.com> wrote: > On Saturday, January 5, 2019 at 2:13:53 PM UTC-6, Peter Percival wrote: >> >> The OP may like to look up "spheres of Dandelin". This >> https://en.wikipedia.org/wiki/Dandelin_spheres, for example, has a nice >> picture. >> > Hi, Peter, I am hoping OP does not mean me. No, "OP" means "original poster", and that is definitely not you. > For my third proof that the ellipse is never a conic, is simple. It may be simple, but it is not a proof, and it is wrong. > Get three figures and elongate. > So you have a ellipse that elongates from 10to1, to 100to1 to 1000to1 > etc etc A cylinder that elongates from 10to1radius, to 100to1radius to > 1000to1 radius etc etc > Now, finally you elongate a cone in 10to1radius to 100to1radius, etc > etc. WTF does this mean? 10to1radius? > Notice that as you elongate a ellipse and a cylinder, they are > symmetrical from side to side and from top to bottom. And you can fit > the ellipse inside the cylinder and make a cut to get the ellipse Yes. > But notice as you elongate a cone, you always have a sharp tip top and > a flaring-out at the bottom. In other words, no ellipse comes out of a > cone. Wrong. The "flaring-out" you envisage at the bottom is compensated for by the sharper angle at which the section plane meets the cone at the bottom, giving an ellipse, symmetrical in two axes. > Simple proof. Simple, yes, but proof, no. It's what happens when you try to use intuition in place of sound mathematics. I seriously recommend you to seek out a photograph of a sectioned cone. You will see that it is symmetrical in two axes. Even better, make yourself a cone out of clay, or butter, or whatever, and cut it yourself. You will see the ellipse, and hopefully then spare us all this nonsense on sci.math. > AP -- Alan Mackenzie (Nuremberg, Germany).
[toc] | [prev] | [next] | [standalone]
| From | moroney@world.std.spaamtrap.com (Michael Moroney) |
|---|---|
| Date | 2019-01-06 18:42 +0000 |
| Subject | Re: My third proof ellipse is never a conic is that the tip end of cone and bottom flared-out end can never yield a 1000to1 ellipse |
| Message-ID | <q0ti5s$cu2$1@pcls7.std.com> |
| In reply to | #430935 |
Alan Mackenzie <acm@muc.de> writes: >Archimedes Plutonium <plutonium.archimedes@gmail.com> wrote: >> On Saturday, January 5, 2019 at 2:13:53 PM UTC-6, Peter Percival wrote: >>> >>> The OP may like to look up "spheres of Dandelin". This >>> https://en.wikipedia.org/wiki/Dandelin_spheres, for example, has a nice >>> picture. >>> >> Hi, Peter, I am hoping OP does not mean me. >No, "OP" means "original poster", and that is definitely not you. He is refering to me. >> For my third proof that the ellipse is never a conic, is simple. >It may be simple, but it is not a proof, and it is wrong. >> Get three figures and elongate. >> So you have a ellipse that elongates from 10to1, to 100to1 to 1000to1 >> etc etc A cylinder that elongates from 10to1radius, to 100to1radius to >> 1000to1 radius etc etc >> Now, finally you elongate a cone in 10to1radius to 100to1radius, etc >> etc. >WTF does this mean? 10to1radius? He seems to mean semimajor axis and semiminor axis. >> Notice that as you elongate a ellipse and a cylinder, they are >> symmetrical from side to side and from top to bottom. And you can fit >> the ellipse inside the cylinder and make a cut to get the ellipse >Yes. >> But notice as you elongate a cone, you always have a sharp tip top and >> a flaring-out at the bottom. In other words, no ellipse comes out of a >> cone. >Wrong. The "flaring-out" you envisage at the bottom is compensated for >by the sharper angle at which the section plane meets the cone at the >bottom, giving an ellipse, symmetrical in two axes. >> Simple proof. >Simple, yes, but proof, no. It's what happens when you try to use >intuition in place of sound mathematics. Yes it's no proof since there is no formula or anything to demonstrate how the curve responds as it moves down the cone. Others have, and have shown the resulting formula matches that of an ellipse. >I seriously recommend you to seek out a photograph of a sectioned cone. >You will see that it is symmetrical in two axes. Even better, make >yourself a cone out of clay, or butter, or whatever, and cut it >yourself. You will see the ellipse, and hopefully then spare us all >this nonsense on sci.math. He has already done stuff like that. He apparently made a paper cone, placed a (circular) Mason jar lid in it at an angle, saw it didn't fit well, and declared that this "proves" an ellipse is not a conic section. No, it demonstrates that an angled cut is not a *circle*.
[toc] | [prev] | [next] | [standalone]
| From | Jan <filmart@gmail.com> |
|---|---|
| Date | 2019-01-06 21:47 -0800 |
| Message-ID | <15a3963a-dab0-49f7-b2f8-aa736e4bbdcc@googlegroups.com> |
| In reply to | #430877 |
On Saturday, January 5, 2019 at 7:19:43 AM UTC-8, Archimedes Plutonium wrote: > Alright the first proof is my historical first proof, in late 2016, I was messing around with the sine function and the cone, ellipse came to mind in that playful messing around. And it struck me, my mind just could not see how a slant cut into the cone yields an ellipse Nevertheless, it does. Go bark some other tree. This one is done. -- Jan
[toc] | [prev] | [standalone]
Page 2 of 2 — ← Prev page 1 [2]
Back to top | Article view | sci.math
csiph-web