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

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SUMMARY

The integral $\int_{|z|=1} |z-1| \, |dz|$ is computed using the parametrization $z(t) = e^{it}$ for $0 \leq t < 2\pi$. The differential $|dz|$ simplifies to $dt$, leading to the evaluation of $\int_{0}^{2\pi} |\cos(t) + i\sin(t) - 1| \, dt$. This integral further simplifies to $\int_{0}^{2\pi} 2\sin\left(\frac{t}{2}\right) \, dt$, which evaluates to 8. The calculations are confirmed to be correct.

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Amer
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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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Looks good to me!
 
Ackbach said:
Looks good to me!
Thanks :o
 

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