Evaluating 3D Integral in Rectangular Coordinates

In summary, evaluating 3D integrals in rectangular coordinates allows us to calculate the volume of a three-dimensional shape or the value of a multivariable function over a specific region in space. The limits of integration for a 3D integral in rectangular coordinates are determined by the boundaries of the region in space and can be defined by the equations of planes or surfaces. The process for evaluating a 3D integral in rectangular coordinates involves setting up the integral with the correct limits of integration, solving for the antiderivative of the function being integrated, and then plugging in the limits and calculating the result. The order of integration does not affect the final result in most cases, but it can sometimes simplify the integral. Some real-world applications of
  • #1
Ions
2
0
Problem: Evaluate (leave in rectangular coordinates):
[tex]

\int_{-1}^{{1}}}\int_{-{\sqrt{1-x^2}}}^{{\sqrt{1-x^2}}}\int_{-{\sqrt{1-x^2-y^2}}}^{{\sqrt{1-x^2-y^2}}}\ \,dz\,dy\,dx
[/tex]
 
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  • #2
Well, start slow. Can you evaluate this integral?
[tex]
\int_{-{\sqrt{1-x^2-y^2}}}^{{\sqrt{1-x^2-y^2}}}\ \,dz
[/tex]
 
  • #3
[tex]

2\int_{-1}^{{1}}}\int_{-{\sqrt{1-x^2}}}^{{\sqrt{1-x^2}}}\2{\sqrt{1-x^2-y^2}}}\,dy\,dx
[/tex]

Supposedly it's easier to make a subtitution u = 1-x^2 at this point but I don't see how...
 
Last edited:

1. What is the purpose of evaluating 3D integrals in rectangular coordinates?

Evaluating 3D integrals in rectangular coordinates allows us to calculate the volume of a three-dimensional shape or the value of a multivariable function over a specific region in space.

2. How do you set up the limits of integration for a 3D integral in rectangular coordinates?

The limits of integration for a 3D integral in rectangular coordinates are determined by the boundaries of the region in space over which the integral is being evaluated. These boundaries can be defined by the equations of planes or surfaces that form the boundaries of the region.

3. What is the process for evaluating a 3D integral in rectangular coordinates?

The process for evaluating a 3D integral in rectangular coordinates involves setting up the integral with the correct limits of integration, solving for the antiderivative of the function being integrated, and then plugging in the limits and calculating the result. This is essentially the same process as evaluating a single-variable integral, but with additional dimensions to consider.

4. How does the order of integration affect the result of a 3D integral in rectangular coordinates?

In general, the order of integration does not affect the final result of a 3D integral in rectangular coordinates. However, in some cases, changing the order of integration can make the integral easier to evaluate or lead to a more simplified result.

5. What are some real-world applications of 3D integrals in rectangular coordinates?

3D integrals in rectangular coordinates have many applications in physics, engineering, and other fields. They can be used to calculate the volume of a solid object, the mass of a three-dimensional body, the center of mass of a system, or the work done by a force on a three-dimensional object, among other things.

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