🔍 Key Concepts

• Difference between an initial great circle course angle and the true course you actually steer on the chart • Relationship between reciprocal courses (adding or subtracting 180°) and direction of travel between two positions • How east and west longitudes affect the general direction of travel on a Mercator chart between the two given points

💭 Think About

• First, picture the two positions on the globe: are you overall going from west to east, or east to west? From north to south, or south to north? • Decide whether the given great circle course angle is pointing from the first position to the second, or from the second back to the first (its reciprocal). • Think about whether the true course you want should be northeasterly, southeasterly, southwesterly, or northwesterly based on the coordinates.

✅ Before You Answer

• Verify whether the initial great circle course angle of 063.8° is measured from LAT 23°00'S, LONG 42°00'W toward LAT 34°00'S, LONG 18°00'E, or the opposite. • Check which answer choice corresponds to the reciprocal of 063.8° (i.e., 063.8° ± 180°) and whether that reciprocal matches the expected general direction between the two points. • Confirm that the correct true course must lead you from the position in the western hemisphere (W longitude) to the one in the eastern hemisphere (E longitude) while going farther south.