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. The position of the vertex is LAT 37°34.9'N, LONG 25°59.0'W. Determine the latitude intersecting the great circle track 600 miles west of the vertex, along the great circle track.
Official USCG Answer & Rule Citation
Correct Answer: Option D — 36°54.9'N
Using the haversine or cosine formula for great circle navigation, the latitude of a point on the track is determined by the vertex latitude and the difference in longitude from the vertex. Applying the spherical trigonometry formula cos(Lat) = cos(Vertex Lat) * cos(Diff Long) yields the latitude 36°54.9'N.
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