Cylindrical / Spherical Coordinates

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Discussion Overview

The discussion revolves around the conversion of Cartesian coordinates into cylindrical and spherical coordinate systems. Participants explore the mathematical expressions involved in these conversions and consider simplifications of specific trigonometric expressions.

Discussion Character

  • Technical explanation
  • Mathematical reasoning

Main Points Raised

  • One participant presents their conversion to cylindrical coordinates, expressing it as r,vector = er,hat + sint(e3,hat), and questions the simplification of the expression 1/cos[tan^-1*(sint)].
  • Another participant proposes that r = √(x² + y² + z²) = √(1 + sin²(t)), seeking clarification on this expression.
  • A different participant questions the equivalence of rad(1 + sin²(t)) to 1/(cos(tan^-1(sint))) and also inquires if r = rad(x² + y²) = 1 is correct for cylindrical coordinates.
  • One participant reiterates the equivalence of rad(1 + sin²(t)) to 1/(cos(tan^-1(sint))) and expresses interest in verifying this analytically, while confirming the cylindrical coordinate expression for r.

Areas of Agreement / Disagreement

Participants express various viewpoints and questions regarding the mathematical expressions, but no consensus is reached on the simplifications or the correctness of the conversions.

Contextual Notes

There are unresolved assumptions regarding the definitions and contexts of the coordinate systems, as well as the mathematical steps involved in the simplifications proposed.

eurekameh
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I'm trying to convert the below Cartesian coordinate system into cylindrical and spherical coordinate systems. For the cylindrical system, I had r,vector = er,hat + sint(e3,hat).
While I do have a technically correct answer for the spherical coordinate system, I believe, I was wondering if there was a way to simplify the expression 1/cos[tan^-1*(sint)]. Thanks.

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##r=\sqrt{x^2+y^2+z^2} = \sqrt{1+\sin^2(t)}##?
 
rad(1+sin^2(t)) = 1/(cos(tan^-1(sint)))?
Also, am I right in thinking r = rad(x^2 + y^2) = 1 for cylindrical coordinates?
 
eurekameh said:
rad(1+sin^2(t)) = 1/(cos(tan^-1(sint)))?
Would be interesting to check this in an analytic way.

Also, am I right in thinking r = rad(x^2 + y^2) = 1 for cylindrical coordinates?
If you use (r,theta,z) as coordinates: Right.
 

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