Calculating Polar Curve Length with Period of 3π: r = psin3(θ/3)

Snoogx
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Homework Statement


Find the length of the polar curve r = psin3(\theta/3)
Hint: The period of the curve is 3\pi

Homework Equations


L = \intsqrt(f(\theta)2 + f'(\theta)2)d\theta

The Attempt at a Solution


I know from the hint that 0\leq\theta\geq3\pi

The only problem I have is how do I start this with "p" in the r-equation. Do I treat it as another variable or is it a constant?
 
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I would treat p as a constant, you're not given necessary information to solve the problem if it were not.
 
If p were not a constant, the equation would not define a curve.
 
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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