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 latitude of the vertex.

Correct Answer: Option D — 37°34.9'N

The vertex of a great circle is the point of highest latitude. Using the formula cos(Lat_vertex) = cos(Lat_initial) × sin(Initial_Course), the calculation involves the sine of the initial course (61.7°) and the cosine of the initial latitude (25.833°), resulting in a vertex latitude of 37°34.9'N.