√(√13 - 2) / (√13 + 2) + √(√13 + 2) / (√13 - 2) = ?

[tex]\displaystyle \sqrt{\frac{\sqrt{13}-2}{\sqrt{13}+2}+\frac{\sqrt{13}+2}{\sqrt{13}-2}} \\ \\ \sqrt{\frac{(\sqrt{13}-2)^2+(\sqrt{13}+2)^2}{(\sqrt{13}+2)(\sqrt{13}-2)}} \\ \\ \sqrt{\frac{13-4\sqrt{13}+4+13+4\sqrt{13}+4}{13-2^2}} \\ \\ \sqrt{\frac{34}{9}} \\ \\ \frac{1}{3}\sqrt{34}[/tex]