Question Number 124063 by Bird last updated on 30/Nov/20
$${find}\:\:\int\int_{{D}} \frac{{arctan}\left(\sqrt{{x}^{\mathrm{2}} +{y}^{\mathrm{2}} }\right)}{{x}+{y}}{dxdy} \\ $$$${D}=\left\{\left({x},{y}\right)\:/\:\mathrm{0}\leqslant{x}\leqslant\mathrm{1}\:{and}\:\mathrm{1}\leqslant{y}\leqslant\mathrm{2}\right\} \\ $$