If \[x\,*y=\sqrt{{{x}^{2}}+{{y}^{2}}},\] find the value of \[\left( 1*2\sqrt{2} \right)\,\left( 1*-2\sqrt{2} \right)\].

• A. \[-7\]
• B. \[0\]
• C. \[2\]
• D. \[9\]