GYRATION, \(= \SQRT {\frac{{{I_{min}}}}{A}}\)Calculation:GIVEN,t = 12 mmFor steel FLAT, \(\begin{ARRAY}{l}{I_{\min }} = \frac{{b{t^3}}}{{12}}\\A = bt\end{array}\)\(\sqrt {\frac{{{I_{\min }}}}{A}} = \;\sqrt {\frac{{b{t^3}}}{{12bt}}} = \frac{t}{{\sqrt {12} }} = \frac{{12}}{{\sqrt {12} }} = 3.46\;mm\)