The above diagram shows where plane A and B can be located in relation to the point where their paths would cross (C). We want to know the distance between A and B (which is c). This forms a triangle, for which the information we are given is SAS (side-angle-side). This fits the Law of Cosines:
c2 = a2 + b2 - 2ac cos C
c2 = 322 + 762 - 2(32)(76) cos 49
c2 ≈ 3608.93
c ≈ 60