The vertex of a great circle track is in...

Question 1 of 2707066636ee928f7522a1c51a58b

The vertex of a great circle track is in LONG 109°E. Which longitude would an eastbound vessel cross the equator?

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Question 1 of 27070

Q

The vertex of a great circle track is in LONG 109°E. Which longitude would an eastbound vessel cross the equator?

🔍 Key Concepts

• Great circle tracks and the location of the vertex • Relationship between longitude of the vertex and longitudes where the great circle crosses the equator • Symmetry of great circles about the equator or a meridian

💭 Think About

• How is the longitude of the vertex related to the longitudes where the same great circle intersects the equator? Think about symmetry. • If the vertex is at 109°E, is it north or south of the equator, and how does that affect where it will cross the equator on an eastbound track? • Among the options, which longitudes form a natural pair or complement with 109°E on a great circle that must cross the equator twice?

✅ Before You Answer

• Confirm that a great circle (other than the equator or a meridian) will intersect the equator at two points. • Check which pair of answer choices are roughly opposite each other in longitude (i.e., differ by about 180°). • Verify which of those possible longitudes is consistent with an eastbound vessel starting from the hemisphere implied by the vertex at 109°E.