Imagine what a triangle looks like in the Klein-Beltrami model. It looks normal, Euclidean…and we’ve already agreed the the sum of the interior angles is less than 180 degrees…so the image of a triangle is a problem.
Imagine what a triangle looks like in the Klein-Beltrami model. It looks normal, Euclidean…and we’ve already agreed the the sum of the interior angles is less than 180 degrees…so the image of a triangle is a problem.