Simple question about parametric equations of a plane in 3D

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Discussion Overview

The discussion revolves around the parametric equations of a plane in 3D, specifically the plane defined by the equation ##z=2##. Participants explore the implications of this equation for the variables ##x## and ##y##, and the nature of dimensionality in relation to parameters.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions whether ##x=t## and ##y=t## can represent the plane defined by ##z=2##, expressing confusion over the graphical representation in Wolfram Alpha.
  • Another participant clarifies that a plane in 3D requires two parameters, suggesting a representation of the plane as ##z=2, x=t, y=u##.
  • A further contribution discusses the concept of parameters, proposing that three parameters would imply a filled 3D cube, while four parameters would extend to higher dimensions.
  • Another participant asserts that since ##x## and ##y## are arbitrary in the equation ##z=2##, they can take any values in ##R##, leading to the conclusion that the plane is indeed the ##x,y## plane at ##z=2##.
  • One participant challenges the introduction of variable ##t##, suggesting it is unnecessary for defining the plane.

Areas of Agreement / Disagreement

Participants express differing views on the representation of the plane and the necessity of parameters. There is no consensus on the best way to define the plane or the role of parameters in this context.

Contextual Notes

There are unresolved assumptions regarding the definitions of parameters and the graphical representation in software tools. The discussion reflects varying interpretations of dimensionality and parameterization.

Who May Find This Useful

This discussion may be useful for individuals interested in linear algebra, 3D geometry, and the conceptual understanding of planes and dimensions in mathematics.

ainster31
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I'm quite rusty in Linear Algebra.

If you have a plane in 3D with the equation ##z=2##, what does ##x## and ##y## equal? Does ##x=t## and ##y=t##?

Because if I graph that in Wolfram Alpha, I don't get a horizontal plane in 3D at ##z=2##: http://www.wolframalpha.com/input/?i=graph+z=2,x=t,y=t
 
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hi ainster31! :smile:
ainster31 said:
If you have a plane in 3D with the equation ##z=2##, what does ##x## and ##y## equal? Does ##x=t## and ##y=t##?

line: one parameter

plane: two parameters :wink:

your plane is z = 2, x = t, y = u​
 
tiny-tim said:
hi ainster31! :smile:line: one parameter

plane: two parameters :wink:

your plane is z = 2, x = t, y = u​

Hmm... what about 3 parameters? What would that result in? A filled 3D cube, right?
 
If x, y, and z are arbitrary, you get the entire space (all of R3).
 
ainster31 said:
Hmm... what about 3 parameters? What would that result in? A filled 3D cube, right?

3 dimensions: 3 parameters …

n dimensions: n parameters …

that's very nearly a definition of dimensions! :smile:
 
z=2 is the equation of a plane in R^3. x and y range over R since they are not specified. So you essentially end up with an x,y plane. In wolfram alpha they just show a line since there doesn't appear to be an easy way to tell it you want R^3. Your initial assumption was correct and variable t shouldn't be introduced.
 

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