Let x = length of each pole.
The minimum length of each pole will be such that they poles are of equal length and symmetric about the vertical axis.
Therefore, consider a right triangle with height = 12, base = 8 and hypotenuse = x.
From the Pythagorean theorem,
x^2 = 8^2 + 12^2 = 208
x = 208^0.5 = 14.42 ft
Answer: Each pole is 14.42 ft long.