Finding the Volume of Two Solids: A Cylindrical Approach

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Hello I need help for this problem, it has been 4 hours trying to do it

Homework Statement



Find the volume of the region of space above the xy-plane, inside the cone z=7−\sqrt{x^{2}+y^{2}} and inside the cylinder x^{2}+y^{2}=4x.

Homework Equations





The Attempt at a Solution



I tried to switch to cylindrical coordinates and I got

0\leq\theta\leq2\pi
0\leqr\leq4cos(\theta)
0\leqz\leq7-r

so,
V=\int^{2\pi}_{0}\int^{4cos(\theta)}_{0}\int^{7-r}_{0}rdzdrd\theta
which doesn't work...

thanks in advance
 
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I think you'll find that θ goes from -π/2 to π/2 .
 
thank you
 
SammyS said:
I think you'll find that θ goes from -π/2 to π/2 .

How did you find these bounds?
 
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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