Question 993958
Use the law of Cosines and draw it.
One leg is 80 (2 hours at 40 mph), the other 70, and the enclosed angle is 45 degrees.

c^2=a^2+b^2-2abcosC; Cos C=sqrt(2)/2
c^2=6400+4900-2(80)(70)*sqrt(2)/2
=3380.4 mi^2
c=58.14 miles