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๐Ÿงต Geometry Question

Anonymous No. 16264456

Does there exist a space-filling rhombic disphenoid?

๐Ÿ—‘๏ธ Anonymous No. 16264466

That's a tesseract from an angle.

Anonymous No. 16264577

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Anonymous No. 16265357

Maybe you should ask your mom about how my thrombic fills the space between her isotittie.

Anonymous No. 16265851

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Anonymous No. 16266303

>>16264456
No.
Source? Divine intuition

Anonymous No. 16266308

Yes, any object is space filling.
What makes space filling curves special is that they're 1d, anything higher than 1d can obviously fill space by making it arbitrarily large.

Anonymous No. 16266343

>>16266308
Wrong: https://mathworld.wolfram.com/Space-FillingPolyhedron.html

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Anonymous No. 16268358

>>16264456
Here's one in 4-dimensions.
disphenoidal 288-cell

The Will Of God No. 16268390

SAFE SPACE

https://www.youtube.com/watch?v=TBvPIAWB_t0

Boards Of Canada No. 16268397

>>16264466
>Telephasic Workshop
https://www.youtube.com/watch?v=he8fMUmxHOU

Anonymous No. 16268883

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Anonymous No. 16268991

It's huge

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Anonymous No. 16280236

>>16264456
Our math isn't advanced enough to answer this question

Anonymous No. 16280310

>>16264466
Tesseracts have quadrilateral faces, moron

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Anonymous No. 16280327

>>16264577
>>16264981
>>16265349
>>16265851
>>16266292
>>16266708
>>16267054
>>16267484
>>16267885
>>16268325
>>16268883
>>16269438
>>16269867
>>16270317
>>16270610
>>16271455
>>16271784
>>16272967
>>16273627
>>16274496
>>16275348
>>16276871
>>16279088
Reporting this thread for spam. 35 replies and ~25 of them are from the same person.

Anonymous No. 16280595

>>16280310
Maybe it's a 4D icosahedron?

Anonymous No. 16280601

>>16280327
I bumped this thread twice because I find it interesting, and nobody has made any interesting posts yet.

Anonymous No. 16281346

>>16280595
https://en.wikipedia.org/wiki/24-cell

๐Ÿ—‘๏ธ Anonymous No. 16281652

>>16281346
I was right. It's a 4D icosahedron. It also goes by the names of icositetrachoron and icosatetrahedroid.

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Anonymous No. 16282671

>>16280327
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๐Ÿ—‘๏ธ Anonymous No. 16282677

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B No. 16282678

>>16282677
Ehm

๐Ÿ—‘๏ธ Anonymous No. 16283179

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ivfvg ynzoqncyhfwf No. 16283261

I'll just analyze the obvious way to try to do it: join edges of the same length together. In order for this to work, at each edge the angle between the two faces that meet there must be [math]2\pi/n[/math] for some [math]n \geq 3[/math]. So let's try to calculate the angles between the faces.

Line the x, y, and z axes up with the rotational axes of symmetry of the disphenoid, and let <a,b,c> be a normal vector to one of the faces. Then <a,-b,-c>, <-a,b,-c>, and <-a,-b,c> are normal vectors to the other faces. The possible angles between the normal vectors are [math]\cos^{-1}\left(\frac{a^2-b^2-c^2}{a^2+b^2+c^2}\right)[/math], [math]\cos^{-1}\left(\frac{-a^2+b^2-c^2}{a^2+b^2+c^2}\right)[/math], and [math]\cos^{-1}\left(\frac{-a^2-b^2+c^2}{a^2+b^2+c^2}\right)[/math], and the angles between the faces are the supplements of these angles. We obtain the result

[math]\cos(\alpha) + \cos(\beta) + \cos(\gamma) = 1[/math]

where [math]\alpha[/math], [math]\beta[/math], and [math]\gamma[/math] are the angles between faces, each of which occurs at two opposite edges.

Now we just search for angles of the form [math]2\pi/n[/math] ([math]n \geq 3[/math]) that satisfy this equation. There is exactly one solution,
[math]\cos(2\pi/4) + \cos(2\pi/6) + \cos(2\pi/6) = 1[/math].
But this would give us a tetragonal disphenoid rather than a rhombic one.

I don't know whether or not there might be a more clever way of doing it that bypasses this issue.

Anonymous No. 16283717

>>16283261
So that's a no, then?

Anonymous No. 16284436

>>16283717
No under the stated assumption. I would guess it's no in general, but I don't have a proof of that.

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Anonymous No. 16286126

>>16264456
>Does there exist a space-filling rhombic disphenoid?
If I go with the definition, provided by >>16266343, then any object capable of tesselation would be "space-filling". Now, I would have expected the isosceles/regular tetrahedron to be a rhombic disphenoid that can fill space, but apparently it can't.
>>16283261
>I don't know whether or not there might be a more clever way of doing it that bypasses this issue.
I don't see how you adressed the issue of tesselation in the first place. What you did, was simply proving that only n = 3 satisfies the condition such that all normal vectors of some object could be expressed as mere variations of a single normal vector.

Anonymous No. 16286139

>>16286126
Frankly, for a single object to be space-filling, it would have to be either completely regular or of a specific shape that would still allow it to fill out space if by rotation alone. And in the latter case, there could be no more than 4 rhombic disphenoids forming another shape that would have to be regular.

Anonymous No. 16286498

>>16286126
Do you understand what the [math]2\pi/n[/math] bit is about?

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Anonymous No. 16287146

>>16286498
>Do you understand what the 2ฯ€/n bit is about?
I forgot about that, quite frankly.

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Anonymous No. 16288710

>>16286139
Why would it have to be regular? It's well-known that non-regular polyhedra can be space filling. For example Escher's solid, or the triakis truncated tetrahedron.

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Anonymous No. 16289599

>>16286139
>Why would it have to be regular?
I haven't specifically called for the condition that they have to be regular in order to be space-filling. What I have done is the following: I have introduced a claim, a condition, that some assembly of non-regular disphenoids would have to form a regular disphenoid in order for the non-regular disphenoids to be space-filling. In two dimensions, the potential max number of space-filling non-regular polygons needed to assemble a regular space-filling polygon would be 6. I can't tell for three or more dimensions.

Anonymous No. 16290006

>>16289599
A regular disphenoid would be a Platonic tetrahedron, which is famously not space-filling. If your claim were true, then there couldn't be any space-filling disphenoids. Since space-filling disphenoids do exist (for example one with sides 6, 6, 4), we can conclude that your premise is false.

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Anonymous No. 16290021

>>16290006
huh. you think you're smarter than me? think again, bucko.

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Anonymous No. 16290151

>>16264456
Rhombic dodecahedra are known to work.

Anonymous No. 16290220

>>16290151
https://polytope.miraheze.org/wiki/Rhombic_disphenoid

Anonymous No. 16290699

>>16264456
no, why do you wanna know?

Anonymous No. 16291013

>>16290699
Can you prove that, or are you making an educated guess?

Anonymous No. 16291307

>>16291013
not doing your homework

๐Ÿ—‘๏ธ Anonymous No. 16291686

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Anonymous No. 16292290

>>16291307
1) What class could this possibly be homework for?
2) Even if it was your answer would be about three weeks too late.
3) If you don't know the answer, you can just not post; no-one's making you reply.

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Anonymous No. 16292306

>>16292290
>1) What class could this possibly be homework for?
Introduction into Algebraic geometry
>2) Even if it was your answer would be about three weeks too late.
You probably hoped someone would solve your exercises in time, but you failed...
>3) If you don't know the answer, you can just not post; no-one's making you reply.
No one's stopping me from replying either.

Uhmmm, did you just get pwned hard? I feel like yes, very much so...

๐Ÿ—‘๏ธ Anonymous No. 16292910

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