A triangle has 270 degrees - Non Euclidean fun
Take or earth and start at any point on the equator.
Head directly north until you reach the north pole (about 10.0000 km).
Turn 90 degrees and walk south (back toward the equator).
After another 10.0000 km you have reached it again.
Once more, turn 90 degrees (same turn, e.g. both left turn at the pole and left turn here) and walk a third 10.000 kilometers.
You are now back where you started, after walking a triangle with 270 degree (3x90) turns on the inside.
Confused? See this nice graphic to verify it:
Head directly north until you reach the north pole (about 10.0000 km).
Turn 90 degrees and walk south (back toward the equator).
After another 10.0000 km you have reached it again.
Once more, turn 90 degrees (same turn, e.g. both left turn at the pole and left turn here) and walk a third 10.000 kilometers.
You are now back where you started, after walking a triangle with 270 degree (3x90) turns on the inside.
Confused? See this nice graphic to verify it: