🔍 Key Concepts

• Mid-latitude sailing formulas for course and distance between two positions • Difference of latitude (DLat) and departure vs. difference of longitude (DLo) • Using the mid-latitude to convert DLo to departure: Dep = DLo × cos(mid-lat)

💭 Think About

• First, determine whether your track is generally NE, NW, SE, or SW based on the two positions. How does that help you estimate the true course quadrant? • Compute the difference of latitude and the difference of longitude in minutes. Then ask: which is larger, and what does that suggest about how steep (north-south vs. east-west) the track is? • Once you find departure using the mid-latitude, think about how to use right-triangle relationships (tan, cos, sin) to get both the course angle and the distance.

✅ Before You Answer

• Be sure you converted degrees and minutes of longitude to minutes correctly before using any formulas. • Confirm you used the correct mid-latitude (average of the two latitudes) and applied cosine to that value, not to a longitude. • After you compute course and distance, check if your course is in the correct quadrant (e.g., something like Nwly or Swly) based on start and end positions before comparing to the choices.