Complex Integration: Solving $\int_{|z|=1} |z-1|.|dz|$

In summary, complex integration is a technique used to calculate integrals involving complex functions by breaking them down into simpler parts and integrating them separately. It represents the area under a curve on the complex plane and the path of integration is important in determining the integral's value. To solve a complex integral involving a circle, the Cauchy integral formula can be used. For the specific integral given, the solution is 0 by substituting in the function and curve into the formula.
  • #1
Amer
259
0
Can you check my work please,
Compute

$\displaystyle \int_{|z|=1} |z-1| . |dz| $

$ z(t) = e^{it} , 0 \leq t < 2 \pi $
$ |dz| =| ie^{it} dt | = dt $

$\displaystyle \int_{0}^{2\pi} |\cos(t) + i\sin(t) - 1 | dt $

$\displaystyle \int_{0}^{2 \pi} \sqrt{(\cos(t) -1)^2 + \sin ^2( t)} \, dt = \int_{0}^{2 \pi} \sqrt{\cos^2(t) - 2\cos(t) +1 + \sin^2(t) } \, dt $

$\displaystyle \int_{0}^{2 \pi} 2\sin \left( \frac{t}{2} \right) dt = 8 $
 
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  • #2
Looks good to me!
 
  • #3
Ackbach said:
Looks good to me!
Thanks :eek:
 

Related to Complex Integration: Solving $\int_{|z|=1} |z-1|.|dz|$

What is complex integration?

Complex integration is a mathematical technique used to calculate the value of integrals involving complex functions. It involves breaking down a complex function into simpler parts and then integrating each part separately.

What is the geometric interpretation of complex integration?

The geometric interpretation of complex integration is that it represents the area under a curve on the complex plane. This curve is defined by the complex function being integrated.

What is the significance of the path of integration in complex integration?

The path of integration is an important factor in complex integration because it determines the values of the integral. Different paths can yield different results, so it is important to choose a path that is consistent with the problem at hand.

How do you solve a complex integral involving a circle?

To solve a complex integral involving a circle, you can use the Cauchy integral formula, which states that the integral of a function over a closed curve is equal to the sum of the function's values at all points inside the curve.

What is the solution to $\int_{|z|=1} |z-1|.|dz|$?

The solution to this integral is 0. This can be found by using the Cauchy integral formula and substituting in the function $f(z)=|z-1|$ and the curve $|z|=1$. The integral becomes $\int_{|z|=1} |z-1|.|dz| = 2\pi i f(0) = 2\pi i |0-1| = 0$.

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