🔍 Key Concepts

• Great circle vertex and what makes it the highest latitude on the track • Relationship between initial course, difference of longitude, and vertex latitude on a great circle • Use of meridional parts / spherical trigonometry for great circle problems

💭 Think About

• How does the initial course at the departure longitude relate to the maximum latitude reached by the great circle? Think about how far east the vertex occurs and how the track curves on a globe. • If you know the initial course and the difference of longitude to the vertex, what trigonometric relationship lets you solve for the vertex latitude? • Compare how a small change in the vertex latitude (within the answer choices) would affect the great circle track shape between these two points.

✅ Before You Answer

• Be clear on what the vertex is: the point of maximum latitude along the great circle. • Confirm which formula connects departure latitude, initial course, and difference of longitude to the vertex before computing. • Check that the latitude you pick is greater than both the departure and arrival latitudes, and reasonable for a North Atlantic great circle between these positions.