Calculating the Length of a Curve with Calculus

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Homework Statement


i'm studying for an exam. and I'm pretty sure i know how do do these types of problems. this is aneven problem in the book so i wanted to know if my answer is right.

Find the length of the curve for r=\sqrt{1+\cos2\theta} , \pi/2\leq\theta\leq\pi/2

Homework Equations



integral of \sqrt{(r^2+(dr/d\theta)^2}[\tex]<br /> <br /> <h2>The Attempt at a Solution</h2><br /> i simplified my r to be \sqrt{2}*\cos\theta<br /> after simplification and plugging into the formula. i got my answer to be \sqrt{2}*\pi
 
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I got the same result. I'm known for making tons of algebra mistakes, so trust my algebra at your own risk. :-p
 
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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