LET the SIDE of SQUARE be\[x\,m.\] then \[{{x}^{2}}=16900\,{{m}^{2}}\]or \[x=\SQRT{16900}\] or \[x=130m.\] Diagonal\[BD=\sqrt{D{{C}^{2}}+B{{C}^{2}}}\] \[=\sqrt{{{130}^{2}}+{{130}^{2}}}=130\sqrt{2}\]