Question 605217
side length = x


Use Phytagoras theorem:
{{{x^2 + x^2 = 16^2}}}
{{{2x^2 = 256}}}
{{{x^2 = 256/2}}}
{{{x^2 = 128}}}
{{{x = sqrt(128)}}}
{{{x = sqrt(64*2)}}}
{{{x = 8sqrt(2)}}}


so, the side length is {{{8sqrt(2)}}}