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

dtl42
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Homework Statement


Find the length of the spiral of r=1/theta for theta\geq2 \pi


Homework Equations


\int\sqrt{r^{2}+r'^{2}}


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 \pi 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:
\int\sqrt{r^{2}+r'^{2}} d\theta

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 .)
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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