The longest rod that can fit in a rectangular box is 17 feet long.
Given:
Length = 12 ft
Width = 9 ft
Height = 8 ft
We need to get the diagonal of the rectangular box. The rectangular box is three dimensional. So, the formula to get it is:
a² + b² + c² = d²
a = width ; b = length ; c = height
9² + 12² + 8² = d²
81 + 144 + 64 = d²
289 = d²
√289 = d
17 = d
