Graphing x=t, y=1/(1+t^2), z=t^2 - Is it a Parabola?

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    Graphing Parabola
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Discussion Overview

The discussion centers around the graphing of the parametric equations x=t, y=1/(1+t^2), and z=t^2, with a particular focus on whether the resulting shape is a parabola. Participants explore the implications of these equations and the visual representation in three-dimensional space.

Discussion Character

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

Main Points Raised

  • One participant expresses uncertainty about the classification of the graph, noting that it resembles a parabola as depicted in their book.
  • Another participant inquires about the ranges for the variables x, y, and z as defined by the parametric equations, suggesting a deeper analysis of the graph's properties.
  • A participant proposes to eliminate the parameter from x and y, leading to the equation y=1/(1+x^2), and describes its characteristics, including a global maximum and horizontal asymptotes.
  • There is a discussion about the concept of shadows cast by the curve onto the xy-plane, questioning whether the resulting shadow corresponds to the graph of y=1/(1+x^2).
  • Several participants express confusion about the graph and its implications, indicating a need for clarification on the relationship between the parametric equations and their graphical representation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on whether the graph is definitively a parabola, and multiple viewpoints regarding the interpretation of the graph and its properties remain present.

Contextual Notes

Participants have not fully explored the ranges of the variables or the implications of the z component in the context of the graph, leaving some assumptions and dependencies unresolved.

ineedhelpnow
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i don't know whether this goes here or under the calculator forum. i want to graph x=t y=1/(1+t^2) and z=t^2 and i keep getting a parabola. is that right because the drawing in my book is like a slanted parabola.

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What are the ranges for $x,\,y,\,z$ as given by the parametric equations?

Also, ignoring each parametric equation in turn, what shadows would then be cast on the relevant planes?
 
:confused:
 
ididntdoitO_o said:
:confused:

Let's ignore $z$ for the moment, and eliminate the parameter from $x$ and $y$, resulting in:

$$y=\frac{1}{1+x^2}$$

We should have a pretty good idea what this looks like...a global maximum at $y(0)=1$, a horizontal asymptote along the $x$-axis in both directions since we have an even function.

So, imagine rays of light parallel to the $z$-axis causing a shadow to be cast by the curve onto the $xy$-plane. Do we get such a curve as described above?
 
(Blush) I am a little confused. i do understand what the graph of y=1/1+x^2 looks like.
 
ididntdoitO_o said:
(Blush) I am a little confused. i do understand what the graph of y=1/1+x^2 looks like.

Okay, now, do you think the shadow I described above would look like the graph of $$y=\frac{1}{1+x^2}$$ for the 3D graph you were given?

Thinking of shadows was the method I was taught back in the dark ages...:D
 

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