Hyperbolic Non-Euclidean World
Ch.16 Move Triangle 2 
Now let us move a triangle again. But this time, we do it on Horocircles (cf. Ch.15). See [Fig 16-1]. Yellow dotted curves are concentric Horocircles. Triangle ABC and the center 
are given. And triangle ABC moved along concentric Horocircles to A'B'C' by reflections. Center works for this movement. New triangle A'B'C' is congruent to the original triangle ABC. But turned angle is zero as we previously discussed (cf. Ch.15). And moved distance of each vertex is different from the others. I do not know what to call this movement. I would say, this time, Horocircle is neither a straight line nor a circle.
[Fig 16-2] left is imitation of [Fig 11-3]. But it's none the better for the change.
We have tried to find plausible parallel translation in the Hyperbolic NonEuclidean World. But it seems all in vain.
Recently, however, a mathematician said that [Fig 11-2] is OK as a parallel translation.
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