🔍 Key Concepts

• Difference in longitude converted to minutes of arc and then to nautical miles • Relationship between latitude and departure on a Mercator chart for short distances • Using basic trigonometry or approximations to find course angle from north or south toward east or west

💭 Think About

• From 1919 to 2019, did you move mainly north–south or east–west? Which direction in each? • Compute the change in latitude and change in longitude (in minutes). Which triangle sides do these represent? • Once you have north/south and east/west components, which function (sine, cosine, or tangent) best gives you the course angle from the meridian?

✅ Before You Answer

• Be sure to convert the longitude difference at the given latitude into nautical miles, not minutes of longitude directly as miles • Confirm whether your course should be east of south or west of south based on the change in longitude • Make sure your final course is expressed as a three‑digit true bearing measured clockwise from true north