Radii and chord form an equilateral triangle. The angle of the larger segment is [tex]360^o-60^o=300^o[/tex].
The length of the larger segment is
[tex]l= \frac{2r\pi\alpha}{360^o}= \frac{2\times 8\pi300^o}{360^o}= \frac{ 16\pi5}{6}= \frac{ 8\pi5}{3}=\frac{ 40\pi}{3}[/tex]