I am struggling with the integration of I=∫π20xcos(x)+sin(x)dx using complex analysis. I used the substitution z=eix→dx=1izdz and hence cos(x)+sin(x)=((z+1z)−i(z−1z)) because we have cos(x)=12(eix+e−ix), and sin(x)=12i(eix−e−ix), and x=−iln(z). However I am not successful to obtain the correct result when using real analysis, which gives I=∫π20xsinx+cosxdx=0.978959918
Any idea how to calculate this integral using complex analysis and Cauchy integral theorem?
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