Setting up triple integrals in different coordinates

In summary, the problem asks to set up the integral ∫f(x,y,z)dV over the region inside the cone z=√x^2+y^2 for 2≤x≤7, using cartesian, spherical, and cylindrical coordinates. The equations for cylindrical and spherical coordinates are provided, and the task is to find the integral borders and convert dV. There is no need for an additional function, as f can be used as f(r, θ, z).
  • #1
anna.schweizer
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Homework Statement



Assume that f(x,y,z) is a continuous function. Let U be the region inside the cone z=√x^2+y^2 for 2≤x≤7. Set up the intregal ∫f(x,y,z)dV over U using cartesian, spherical, and cylindrical coordinates.

Homework Equations



CYLINDRICAL COORDINATES
  • x=rcosθ
  • y=rsinθ
  • z=z

SPHERICAL COORDINATES
  • ρ^2 =x^2 + y^2 + z^2
  • x = ρsin(phi)cos(θ)
  • y=ρsin(phi)sin(θ)
  • z=ρcos(phi)

The Attempt at a Solution



Do Ineed to have a function for the inner two integrals?

For my limits on integration for Cartesian coordinates are
z = x^2 + y^2 -4 and z = x^2 + y^2 -25
I DON'T KNOW FOR X
and y = 2 and y = 5

For my limits on the spherical coordinates are
θ=2π, θ=0; and ρ=2, ρ=5

I DON'T KNOW IF WHAT I'M DOING IS RIGHT OR NOT. I'M LOST :(

Please and thank you for your help!
 
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  • #2
Do Ineed to have a function for the inner two integrals?
Your function is just f, you can use it as f(r, θ, z) and similar for spherical coordinates, that is fine.
Your task is to find the integral borders and to convert dV.

I DON'T KNOW FOR X
That is given in the problem statement, and please don't write in caps.

Your attempt at a solution uses equations different from the problem statement.
 

What are the different coordinate systems used in setting up triple integrals?

The most commonly used coordinate systems for setting up triple integrals are Cartesian coordinates, cylindrical coordinates, and spherical coordinates.

How do I convert between different coordinate systems?

To convert between different coordinate systems, you can use the appropriate conversion formulas. For example, to convert from Cartesian coordinates to cylindrical coordinates, you can use the formulas x = rcos(theta), y = rsin(theta), and z = z. To convert from Cartesian coordinates to spherical coordinates, you can use the formulas x = rsin(phi)cos(theta), y = rsin(phi)sin(theta), and z = rcos(phi).

What is the purpose of using different coordinate systems in triple integrals?

Using different coordinate systems in triple integrals allows for a more efficient and simplified calculation of the integral. It also allows for integration over more complex and irregularly shaped regions.

How do I determine the limits of integration in different coordinate systems?

The limits of integration in different coordinate systems can be determined by visualizing the region of integration and understanding how the coordinates change over that region. It may also be helpful to draw a diagram and use the conversion formulas to determine the corresponding limits in each coordinate system.

Are there any limitations to using different coordinate systems in triple integrals?

While different coordinate systems can make the calculation of triple integrals more efficient, they may not always be appropriate for certain regions of integration. It is important to consider the shape and symmetry of the region when choosing the appropriate coordinate system.

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