Direct triangle, three sides are arithmetic sequence, known area is 12. Find perimeter

Direct triangle, three sides are arithmetic sequence, known area is 12. Find perimeter

If the tolerance is B, then
(x-b)*x=12*2
x*x+(x-b)*(x-b)=(x+b)*(x+b)
The solution is b = √ 2, x = 4 √ 2
Perimeter 12 √ 2