Caption: Differential geometry uses the techniques of calculus in the analysis of geometry.
In the displayed image, differential geometry is exemplified by a hyperbolic triangle on hyperbolic paraboloid (a saddle shaped surface) and two diverging ultraparallel lines.
The hyperbolic triangle has vertex angles that sum to less than 180°.
The ultraparallel lines have a unique line that is perpendicular to the both of them at their point of closest approach.
Credit/Permission: User:LucasVB,
2007 /
Public domain.
Image link: Wikipedia.
Local file: local link: differential_geometry.html.
File: Relativity file:
differential_geometry.html.