If a 3D object has 4 points. why use x,y,z to describe 3D?

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The discussion centers on the confusion surrounding the use of x, y, and z coordinates to describe 3D space, particularly in relation to the tetrahedron, which has four points. It is clarified that while a tetrahedron has four vertices, only three coordinates are necessary to define a point in 3D space, as each point can be represented by three axes of measurement. The conversation also touches on the concept that n-dimensional space requires n+1 points to define it, but only n coordinates are needed for representation. Additionally, the idea of using alternative coordinate systems is mentioned, emphasizing that using more than three coordinates in 3D space leads to redundancy. Overall, the thread highlights the complexities of geometric representation and the importance of understanding coordinate systems.
  • #31
Look, there's something ridiculous going on. There are standards to mathematics. These standards were established for reasons that most people have forgotten - some going back to the ancient Greeks.

DaveC, you are trying to uphold a particular standard, but really aren't providing any good reasons for it.

Darken-Sol: You really need to think about what is meant by "direction".

If you start out at the origin, there are an infinite number of directions you could travel. (Up, down, left, right, forward, backwards, diagonally up-right, diagonally down-right, diagonally forward-right, etc...).

We don't want to have to name all these directions individually, so we come up with a systematic way of naming them. This involves using axes x,y, and z.

The idea is that any particular direction you might want to go can be described using only these three elementary directions.

We don't want to give the direction half-way between up and left a special name. We can already describe it as x/2 + y/2. To give it an entirely new name would be redundant.

Similarly, your directions a,b, and c are redundant, because we can describe them as -x, -y, and -z. Why should we give new names to things we can already describe using x, y, and z?
 
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  • #32
klackity said:
DaveC, you are trying to uphold a particular standard, but really aren't providing any good reasons for it.

The only standard I'm trying to uphold is using the minimum number of properties to uniquely describe something. When using more than the minimum number, you get redundant or conflicting results. Other than that, I'm good.
 
  • #33
damn i was hoping someone would look into it and see if there was anything to it. when i was researching a tetrahedral coordinate system, i came across fuller, he apparently had the same idea. some kid in breckinridge, mn also thought of it. he asked for help developing the math processes to make it useful. while traversing links about it i come across fibiannaci numbers alot. and also i don't see a lot of cubic structures in nature. i am curious if it was passed over for a reason or if it was overlooked. perhaps it would work, but we are already dependant on xyz. i just don't know enough yet to come to a conclusion myself.
 
  • #34
Darken-Sol said:
damn i was hoping someone would look into it and see if there was anything to it. when i was researching a tetrahedral coordinate system, i came across fuller, he apparently had the same idea. some kid in breckinridge, mn also thought of it. he asked for help developing the math processes to make it useful. while traversing links about it i come across fibiannaci numbers alot. and also i don't see a lot of cubic structures in nature. i am curious if it was passed over for a reason or if it was overlooked. perhaps it would work, but we are already dependant on xyz. i just don't know enough yet to come to a conclusion myself.

Uuh, can you give a reference of this? I searched for tetrahedral coordinate systems and I found nothing interesting...
 
  • #35
Darken-Sol: Did you not read my post about simplexes (the generalization of tetrahedrons)?

It's been done before. Here's a wikipedia article on exactly what I told you about: http://en.wikipedia.org/wiki/Barycentric_coordinate_system_(mathematics)

The wikipedia article uses linear algebra, but you can define Barycentric coordinates using compass and straightedge constructions (I think).

But I don't think anyone here is going to bother explaining the geometry to you.
 
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  • #36
klackity said:
Darken-Sol: Did you not read my post about simplexes (the generalization of tetrahedrons)?

It's been done before. Here's a wikipedia article on exactly what I told you about: http://en.wikipedia.org/wiki/Barycentric_coordinate_system_(mathematics)

The wikipedia article uses linear algebra, but you can define Barycentric coordinates using compass and straightedge constructions (I think).

But I don't think anyone here is going to bother explaining the geometry to you.

i checked out a few links and bookmarked them. i only get about four hours a day to study, but now that its the weekend i'll go over them. this last one seems to be exactly what i was liiking for. i just read the first couple paragraphs then came back to express my appreciation for your time. thanks for the refocus.
 

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