Equation general of conic in polar coordinates

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Discussion Overview

The discussion revolves around the general equation of conics in polar coordinates, contrasting it with known forms in Cartesian coordinates. Participants explore whether a general form exists in polar coordinates beyond the parametric representation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note the existence of a general conic equation in Cartesian coordinates and inquire about its equivalent in polar coordinates.
  • One participant suggests that expressing the general Cartesian equation in terms of polar coordinates would yield a complex form, indicating that the parametric representation is more suitable for conics.
  • Another participant emphasizes that they are not seeking a transformation but rather a general expression for conics in polar coordinates that is independent of Cartesian formats.
  • A later reply questions the necessity of avoiding transformations, suggesting that deriving the polar form from the Cartesian equation may be a natural approach.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the existence of a general form for conics in polar coordinates, with differing views on the relevance of transformations and the complexity of such expressions.

Contextual Notes

Participants express uncertainty regarding the complexity of the polar form derived from Cartesian coordinates and the implications of the center's significance in polar representations.

Jhenrique
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The conic equation has 2 versions in cartesian coordinates:

The general: ##Ax^2 + Bxy + Cy^2 + Dx + Ey + F = 0##
And the parametric: ##y^2 = 2px + (e^2-1)x^2##

In polar coordinates, I known just the parametric: ##r = \frac{p}{1+e\cos(\theta)}##
But exist a general form too?
 
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You can express x and y in your general equation in terms of r and θ to get the general form. I think it will look quite messy. The parametric uses the "right" coordinate system, where the equation has a nice form. Usually there is no point in polar coordinates if the center does not have a special meaning.
 
mfb said:
You can express x and y in your general equation in terms of r and θ to get the general form. I think it will look quite messy. The parametric uses the "right" coordinate system, where the equation has a nice form. Usually there is no point in polar coordinates if the center does not have a special meaning.

But what you are suggesting is a transformation... I'm not looking for this, but yes by a general expression/format that is a conic but is independent of the cartesian format...
 
Well, you look for the result of a transformation. Isn't it natural to just do this transformation then?
 
Ahhh, does not matter... thanks of anyway
 

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