The great circle distance from LAT 08°50.0'N, LONG 80°21.0'W to LAT 22°36.0'N, LONG 128°16.0'E is 7801 miles and the initial course is 318°45' T. The latitude of the vertex is 49°20.6'N. What is the longitude of the vertex?

Correct Answer: Option D — 162°41'W

Vertex longitude is calculated using spherical trigonometry formulas from Bowditch, where the difference in longitude from the departure point to the vertex is found using the cotangent of the initial course and the tangent of the departure latitude.