🔍 Key Concepts
• Use the great circle (GC) formula for distance on a sphere using both latitudes and the difference in longitude
• Compare the result to what a rhumb line (loxodrome) distance and course might roughly look like to see if your answer is reasonable
• Remember that initial GC course can differ noticeably from the midpoint or average bearing—it is based on conditions at the point of departure
💭 Think About
• First, compute or estimate the difference in longitude and decide if the shorter GC route is eastbound or westbound across the Atlantic
• Use the GC distance relationship involving cos(Dist/R), sin(lat1), sin(lat2), and cos(Δlong), and see which choice is in the right distance range
• Once you have an approximate distance, use the initial course formula for great circles, then check which option’s course direction (NE, SE, etc.) makes sense from the starting position
✅ Before You Answer
• Verify whether the shorter arc between the two longitudes is being used (Δλ less than 180°)
• Check if your computed distance is in nautical miles, not degrees of arc—multiply degrees of great-circle arc by 60 NM per degree
• Confirm that the initial course is from the departure point (25° 50.0' N, 77° 00.0' W), and that its general quadrant (NE, NW, SE, SW) matches the geometry of the problem