Question 1093776
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The problem says nothing, whether they go in 

    a) the same direction (?); 
    b) in the opposite directions (?); 
    c) in the perpendicular directions (?);   or 
    d) in some other ways.


Meanwhile, the easy analysis shows that 

   case a) is impossible;

   case b) is impossible.

   Case c) is possible; then you have 3-4-5 right angled triangle with the Alan's leg of 4 miles.
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