Highest-latitude point (vertex) of a great-circle track - where the track runs true east-west. Napier’s Rules of circular parts.
Formula
$$ \cos L_V = |\cos L \cdot \sin C| $$
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| $L$ | Any known latitude on the track | ° | input |
| $C$ | Initial course at that point | °T | input |
| $L_V$ | Vertex (highest) latitude | ° | result |
Sources
- Bowditch - American Practical Navigator Ch.24.