Could any one tell me what are the fundamental contrasts with postulates of Euclidean Geometry and Spherical Geometry?
I myself see these things, please tell me if there are more:
Lines in EG are great Circles in SG, we can extend infinitely a line in EG but there is no great circle in a sphere which has arbitrary radius.
Parallel Line exists in EG but not in SG as any two great circle meets in two points also a contrast that in EG any two non parallel line meets only at one pt.
Sum of angles exceeds $180$ degree in SG.
along with this I would like to ask: is there any spherical triangle whose angles add up to exacly $180$ degree, which euclidean postulates is violating and why please tell me