I would have asked this on a math community but I couldn’t find an active one.
In a spherical geometry, great circles are “straight lines”. As such, a triangle can have two or even three right angles to it.
But what if you go the long way around the back of the sphere? Is that still a triangle?
(Edit:) I guess it’s a triangle! Fair enough; I can’t think of what else you would call it. Thanks, everyone.
If you were to walk this route along the surface of the earth, you would walk in perfectly straight lines apart from the three turns.
No such thing. Even if you were walking on a surface with no change in elevation, the acceleration due to gravity would cause your path to be curved as it followed the curvature of the planet.