Question

the perimeter of a square in which A=169cm square root 2?

Answer 1

I'm guessing you mean:
$A = 169 \sqrt{2}$

If not, correct me. 

So, then the perimeter of a square is just 4*A, which in this case would be:
$4(169 \sqrt{2}) = 676 \sqrt{2}$

And that would be your answer: $676 \sqrt{2}$ units²