Aria triunghiului echilateral = A, L = latura triunghi, si R = raza cercului circumscris
[tex]L = R\sqrt{3}[/tex]
[tex]A = \frac{L^2\sqrt{3}}{4} \implies A = \frac{3R^2\sqrt3}{4}[/tex]
[tex]3R^2\sqrt3=4\cdot 25\sqrt3 \implies R^2 =\frac{100}{3}[/tex]
[tex]R = \sqrt{\frac{100}{3}} = \frac{10}{\sqrt3}= \frac{10\sqrt3}{3}[/tex]
