Question Number 118323 by Dwaipayan Shikari last updated on 16/Oct/20
$${Prove}\:{that}\: \\ $$$$\zeta\left(\mathrm{1}−{s}\right)=\mathrm{2}^{\mathrm{1}−{s}} \pi^{−{s}} {cos}\left(\frac{{s}\pi}{\mathrm{2}}\right)\Gamma\left({s}\right)\zeta\left({s}\right) \\ $$