Polar Regions: Area, Arc Length, and Surface Area

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Homework Statement



Consider the graph (see attachment) of r = 1 +2cos\Theta in polar coordinates. SET UP integrals to find
1. the area inside the large loop minus the area of the small loop.
2. the arc length of the small loop
3. the surface area of the surface formed by revolving the large loop about the initial ray.


Homework Equations



area A of the polar region
A = \int\frac{1}{2}(f(\Theta))^{2}d\Theta with upper limit b and lower limit a.

arc length AL of the polar region:
AL = \int\sqrt{r^{2}+(\frac{dr}{d\Theta})^{2}} d\Theta with upper limit b and lower limit a.

not sure what equation i need to figure out the surface area one

The Attempt at a Solution



I'm pretty much lost when it comes to the entire problem, and have no ideas where to start. Please help!
 

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  • Calc Graph.jpg
    Calc Graph.jpg
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You've got the equations right. You just have to figure out what to use for the bounds. For 1, if you want to encompass only the larger arc, what should the upper bound be?
 
Well if the 4π/3 ray moved in a counterclockwise motion until the 2π/3 ray, then the ray would sweep the entire area of the large loop. But that would mean doing an integral from a lower bound of 4π/3 to the upper bound of 2π/3. This to me doesn't seem right since usually the lower bound is smaller than the upper bound.
 
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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