You depart LAT 26°03'S, LONG 10°28'E, for...

🔍 Key Concepts

• Parallel sailing uses the latitude and difference of longitude to find distance on a parallel, not along a meridian. • On the same latitude, the distance between two meridians = (difference of longitude in minutes) × cos(latitude). • You must decide first whether your course is east (090°T) or west (270°T) based on how longitude changes.

💭 Think About

• From LONG 10°28'E to LONG 01°16'W, are you moving toward increasing east longitude or toward west longitude across the Prime Meridian? What does that say about your true course (090°T vs 270°T)? • Compute the total difference in longitude: carefully combine the east and west longitudes to get Δλ in degrees and minutes. Is it simply a subtraction, or do you add when crossing from E to W? • Once you have Δλ in minutes of arc, how do you apply cos(latitude) to get the actual distance on that parallel? Compare your result with the two remaining distance options.

✅ Before You Answer

• Confirm the sign and direction of the longitude change (E to W) before choosing 090°T or 270°T. • Convert Δλ to minutes of arc (degrees × 60) before multiplying by cos(latitude). • Make sure you use the given latitude (26°03'S) in the cosine, not the longitude, and check that your distance is close to one of the two numerical choices.

You depart LAT 26°03'S, LONG 10°28'E, for LAT 26°03'S, LONG 01°16'W. What are the course and distance by parallel sailing?

090°T, 547.2 miles

090°T, 632.5 miles

270°T, 547.2 miles

270°T, 632.5 miles

🔍 Key Concepts

💭 Think About

✅ Before You Answer