Question Number 110154 by mathdave last updated on 27/Aug/20
$${prove}\:{that}\: \\ $$$$\int_{\mathrm{0}} ^{\mathrm{1}} \int_{\mathrm{0}} ^{\mathrm{1}} \frac{\mathrm{tanh}^{−\mathrm{1}} \left(^{\mathrm{4}} \sqrt{{x}}\right)\mathrm{tanh}^{−\mathrm{1}} \left(^{\mathrm{4}} \sqrt{{y}}\right)}{{x}\sqrt{{y}}}=\pi^{\mathrm{2}} \\ $$