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\mathrm{a}=\sqrt{3}:\left.\frac{1}{\sqrt{3}} \operatorname{acrtan}\left(\frac{\mathrm{x}}{\sqrt{3}}\right)\right|_{-1} ^{1}=\frac{1}{\sqrt{3}}\left\{\arctan \left(\frac{1}{\sqrt{3}}\right)-\arctan \left(\frac{-1}{\sqrt{3}}\right)\right\}