We have to calculate the length of the rail.
We can imagine the rail as forming a right triangle as:
Then, we can use the Pythagorean theorem to find the length of the rail (x):
[tex]\begin{gathered} x^2=5^2+8^2 \\ x^2=25+64 \\ x^2=89 \\ x=\sqrt{89} \\ x\approx9.4 \end{gathered}[/tex]Answer: the length is approximately 9.4 feet.