Use Cauchy Residue Theorem to find the integral

In summary, the Cauchy Residue Theorem is a mathematical theorem used to evaluate integrals along closed curves in complex analysis. It states that the integral of an analytic function around a closed curve is equal to the sum of the residues of the function at its isolated singularities inside the curve. To apply this theorem, one must identify the singularities, find the residues, and use the formula to evaluate the integral. The theorem only applies to simple closed curves and has limitations such as the function being analytic on the curve and the curve not intersecting any singularities.
  • #1
DanniHuang
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Homework Statement



To find the integral by Cauchy Residue Theorem and apply substitution method.

Homework Equations



To show: ∫[itex]^{2∏}_{0}[/itex][itex]\frac{cosθ}{13+12cosθ}[/itex]=-[itex]\frac{4∏}{15}[/itex]

The Attempt at a Solution


The solution I have done is attached. It is different as what the question wants me to show. I do not know where I did it wrong.
 

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  • #2
Otherwise it looks fine to me, except that
[tex] 6z^3+13z^2+6z = 6 z(z+2/3)(z+3/2) \neq z(z+2/3)(z+3/2) [/tex]
 

FAQ: Use Cauchy Residue Theorem to find the integral

What is the Cauchy Residue Theorem?

The Cauchy Residue Theorem is a mathematical theorem used in complex analysis to evaluate integrals along closed curves. It states that if a function is analytic inside and on a simple closed curve, then the integral of that function around the curve is equal to the sum of the residues of the function at its isolated singularities inside the curve.

How do you apply the Cauchy Residue Theorem to find an integral?

To apply the Cauchy Residue Theorem, you must first identify the singularities of the function inside the closed curve. Then, you must find the residues of the function at those singularities. Finally, you can use the formula of the Cauchy Residue Theorem to evaluate the integral.

Can the Cauchy Residue Theorem be used for all integrals?

No, the Cauchy Residue Theorem can only be used for integrals of analytic functions along closed curves. If the function is not analytic, or the curve is not closed, then the theorem cannot be applied.

What is the difference between a simple closed curve and a closed contour?

A simple closed curve is a curve that does not intersect itself, while a closed contour is a curve that can intersect itself or have multiple components. The Cauchy Residue Theorem only applies to simple closed curves.

Are there any limitations to using the Cauchy Residue Theorem?

Yes, there are certain limitations to using the Cauchy Residue Theorem. It can only be used for integrals along closed curves, and the function must be analytic inside and on the curve. Additionally, the curve must not intersect any singularities of the function. If any of these conditions are not met, the theorem cannot be applied.

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