The great circle distance from LAT 25°50'N, LONG 77°00'W to LAT 35°56'N, LONG 06°15'W is 3616 miles, and the initial course is 061.7°T. Determine the longitude of the vertex, given the latitude of the vertex as 37°34.9'N.

Correct Answer: Option B — 25°59.0'W

Great circle vertex longitude is determined using spherical traverse tables or navigational formulas from Bowditch, applying the known vertex latitude, departure coordinates, and initial course angle.