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MAT334-2018F => MAT334--Tests => Quiz-4 => Topic started by: Victor Ivrii on October 26, 2018, 05:55:01 PM

Title: Q4 TUT 5101
Post by: Victor Ivrii on October 26, 2018, 05:55:01 PM
Evaluate the given integral using Cauchy’s Formula or Theorem. Orientation counter-clockwise:
$$
\int_{|z|=1} \frac{\sin (z)\,dz} {z}.
$$
Title: Re: Q4 TUT 5101
Post by: Jeffery Mcbride on October 26, 2018, 05:55:29 PM

\begin{equation*}
\int _{|z|\ =\ 1}\frac{sin( z)}{z}\\
\\
=\int _{|z|\ =\ 1} \ \frac{sin( z)}{z\ -\ 0}\\
\\
Set\ \zeta ( z) \ =\ sin( z)\\
\\
So,\ by\ Cauchy's\ formula,\\
\\
f( z) \ =\ \frac{1}{2\pi i}\int _{\gamma } \ \frac{\zeta ( z)}{\zeta \ -\ z}\\
\\
\int _{|z|\ =\ 1} \ \frac{sin( z)}{z\ -\ 0} \ =\ ( 2\pi i) \zeta ( 0) \ \\
\\
=\ ( 2\pi i)( sin\ 0) \ =\ 0\ \ \\
\end{equation*}
Title: Re: Q4 TUT 5101
Post by: Victor Ivrii on October 27, 2018, 02:17:38 PM
Do not try to post solutions for many very similar problems. No double-dipping!