Spherical geometry
Spherical geometry(It comes, whether ゅ bear to go back and forth, く) geometry, non-euclidean geometry. The Arabic astronomical scholarBatter kneeAstronomical observation was done making use of this.
Definition of terminology
- spherical surfacePointWith it does.
- SphereGreat circleStraight lineWith it does.
- If as for the straight line which passes by 2 points the 2 points there is no symmetrical position vis-a-vis the center of sphere it becomes settled uniquely.
- The angle where two great circles mix 2 straight linesAngleWith it does.
Character of spherical geometry
- All straight lines mix in 2 points.
- triangle becomes always to be larger than 180 degrees smaller than 540 degrees.
Related item
- elliptic geometry
- Riemannian geometry
- differential geometry
