Why OH Why_3D Parametric Equations

Click For Summary

Discussion Overview

The discussion revolves around the learning and understanding of equations of lines and planes in three-dimensional space, particularly focusing on the parametrization approach represented by the equation r = ro + t*v. Participants explore whether this is the only method to learn these concepts and express varying levels of comfort with the formalism.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant questions the necessity and difficulty of learning line and plane equations through the parametrization method, suggesting it may not be the only approach.
  • Another participant argues for the advantages of parametrization, stating it provides a unified way to describe various curves and surfaces, emphasizing its importance in understanding geometry.
  • A third participant acknowledges the existence of other definitions but suggests that they may be less intuitive, prompting a discussion about the nature of definitions and their geometric intuitiveness.
  • Participants discuss alternative expressions for geometric shapes, questioning their intuitive understanding and relevance to the topic at hand.
  • One participant expresses a lack of geometric intuition regarding certain mathematical expressions, indicating a desire for more intuitive methods.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the parametrization approach is the only or best way to learn about lines and planes in 3D. There are competing views on the intuitiveness of different methods and definitions.

Contextual Notes

Some participants express uncertainty about the geometric intuition behind certain mathematical expressions and definitions, highlighting the subjective nature of understanding in this context.

karen03grae
Messages
79
Reaction score
0
Our lecture today covered Equations of Lines and Planes in 3D.

Is this the only approach to learning line and plane equations in 3-d?

Honestly do we need r = ro + t*v?

To me this seems like a very hard way to learn equations of lines and planes.

Maybe I should learn it to be a more well-rounded Cal. student.

Any suggestions on if this is the only way to determine Eq.s of lines/ planes?

Thanx!
 
Physics news on Phys.org
You are approaching this with the wrong attitude.
Rather than bemoaning your initial problems with this, you should ask yourself:
What are the advantages of thinking of lines in terms of parametrizations?
The immediate advantage, is that essentially all types of CURVES (not just straight lines!) is a ONE-DIMENSIONAL object!
This one-dimensionality is expressed in that a single parametrization variable is needed to describe the curve.

Further, a surface/area is essentially a two-dimensional object; you can describe any surface/area with two independent parametrization variable.

So, you have through parametrization an elegant unification of many seemingly diverse objects.

And yes, this formalism is absolutely needed.
 
Or, one may say "I learned a definition today. I didn't like it", well, sorry, it's a definition. It's not the only one, but it is one the others are less intuitive. Deal with it. Feel free to offer another one: you imply you know other equations of straight lines in R^3. [crap analogy: I learned that chien was dog in french today. why? dog is such a shorter word, and french is a romance language so why isn't it closer to canus?...]

Incidentally, do you get any geometric intuition from:

(x-a) wedge b=c, or (x-a)/p=(y-b)/q=(z-c)/r

or understan that these are just ways of DESCRIBING geometric shapes, not defining them.

Show that two arbitrary lines do or do not intersect, eg the line L(1) passing through the points (1,1,0) and (0,0,2) and the line L(2) passing through the points (1,0,0) and (3,2,1)...
 
Last edited:
matt grime said:
It's not the only one, but it is one the others are less intuitive.

Okay, I was wondering if there was a more intuitive way out there. But I suppose this way is fine.

matt grime said:
Incidentally, do you get any geometric intuition from:

(x-a) wedge b=c, or (x-a)/p=(y-b)/q=(z-c)/r
No.

K, I'm going to work on my homework now.
 

Similar threads

  • · Replies 13 ·
Replies
13
Views
4K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 8 ·
Replies
8
Views
9K
  • · Replies 11 ·
Replies
11
Views
11K
  • · Replies 7 ·
Replies
7
Views
4K
Replies
4
Views
3K
  • · Replies 16 ·
Replies
16
Views
3K