Shortcut (Formula):

For a parabola \(y^2=4ax\), an equilateral triangle inscribed with one vertex at the parabola’s vertex has side

\[ s = 8a\sqrt{3}. \]

Here \(y^2=8x \Rightarrow 4a=8 \Rightarrow a=2\). Hence

\[ s = 8\cdot 2\sqrt{3}=16\sqrt{3}. \]

Final Answer: \(16\sqrt{3}\)