[tex]8 \sqrt{5} is \: the \: length[/tex]
Step-by-step explanation:
[tex]( {16})^{2} = ( {x})^{2} - ( {8})^{2} \\ 256 = {x}^{2} - 64 \\ 256 + 64 = {x}^{2} \\ \sqrt{320} = \sqrt{ {x}^{2} } \\ 8 \sqrt{5} = x[/tex]
