🔍 Key Concepts

• Difference of longitude on a parallel of latitude • Departure formula: Dep = Distance × cos(latitude) • Converting departure in minutes of longitude to degrees and minutes, and applying E/W sign correctly

💭 Think About

• First, at latitude 51°48.0'S, will one degree of longitude be more or less than 60 nautical miles? How does that affect how far your longitude changes when steaming west? • Compute the departure (east-west distance) from the 179‑mile run on course 270°. Once you have that in nautical miles, how do you turn that into minutes of longitude at this latitude? • From a starting longitude of 178°35.0'W, moving westward, will your longitude numbers get larger W, cross 180°, or move toward E? How does that influence which options are plausible?

✅ Before You Answer

• Confirm you are using cosine of the latitude (51°48.0') for departure, not sine • Make sure you convert between nautical miles and minutes of longitude properly at this latitude • Check whether your final longitude should be labeled E or W based on westward motion from 178°35.0'W and whether you cross the 180° meridian