Answer:
A. 
B. 42.4 inches. It will fit.
Step-by-step explanation:
A.
Let s = the length of the diagonal across the bottom of the box.

Therefore, 
B.
Let r = the length from a bottom corner to the opposite top corner.

Therefore, the length of the longest tube that will fit in the box is 42.4 inches.
Since the fishing rod is only 42 inches long, which is less than 42.4 inches, by only 0.2 inches, it means it will still fit.
173.014925373 to be exact
Answer:
3-1 = 2 units is the distance between the points.