Hvad er vinkelsummen for en trekant tegnet på en kugle ?
What is the total degree sum of the angles in a triangle drawn on a sphere?
From Amanda Briney
Appearance on Maps
It is important to note though that when long distance routes following great circles are drawn on Mercator maps, they look curved and longer than straight lines along the same routes. In reality though, the longer looking, curved line is actually shorter because it is on the great circle route. [...]
Read more: http://geography.about.com/od/understandmaps/a/greatcircle.htm