{(α^{2} + η)}^{1 / 2} + \frac{1}{2} α \ln η - α \ln ({(α^{2} + η)}^{1 / 2} + α) = \arccos (\frac{x}{{(1 + α^{2})}^{1 / 2}}) + \frac{α}{2} \ln (\frac{1 + α^{2} + (α^{2} - 1) x^{2} - 2 α x {(1 + α^{2} - x^{2})}^{1 / 2}}{(1 + α^{2}) (1 - x^{2})})