Calculating Polar Arc Length for r=1/theta from 2 Pi to Infinity | Homework Help

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SUMMARY

The discussion focuses on calculating the polar arc length of the curve defined by r=1/theta for theta ranging from 2 Pi to infinity. The formula for polar arc length, \int\sqrt{r^{2}+r'^{2}} d\theta, is correctly identified, but the convergence of the integral remains uncertain. Participants confirm that the integral may diverge, indicating that the hyperbolic spiral represented by this equation does not yield a finite length over the specified interval.

PREREQUISITES
  • Understanding of polar coordinates and polar curves
  • Familiarity with calculus, specifically integration techniques
  • Knowledge of hyperbolic spirals and their properties
  • Ability to evaluate improper integrals
NEXT STEPS
  • Study the properties of hyperbolic spirals in detail
  • Learn techniques for evaluating improper integrals
  • Explore the convergence criteria for integrals involving infinite limits
  • Review the derivation and application of the polar arc length formula
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Students studying calculus, particularly those focusing on polar coordinates and arc length calculations, as well as educators seeking to enhance their understanding of hyperbolic spirals.

dtl42
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Homework Statement


Find the length of the spiral of r=1/theta for theta[tex]\geq[/tex]2 [tex]\pi[/tex]


Homework Equations


[tex]\int[/tex][tex]\sqrt{r^{2}+r'^{2}}[/tex]


The Attempt at a Solution


I thought of the formula for polar arc length, which is the integral of the square root of the sum of the square of r and the square of r'. I tried to evaluate this from 2 [tex]\pi[/tex] to infinity, but could not come up with a definitive answer. I think it might be infinity, but cannot show it legitimately
 
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dtl42 said:
[tex]\int[/tex][tex]\sqrt{r^{2}+r'^{2}} d\theta[/tex]

You probably aren't getting help because you haven't shown any work. What did you set up as your integrand? Your limits for the improper integral are correct; it really is possible that the integral doesn't converge. (This curve is called a hyperbolic spiral -- see http://mathworld.wolfram.com/HyperbolicSpiral.html .)
 

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