Geometrical researches on the theory of parallels (1914)
Lobachevskiĭ, N. I. (Nikolaĭ Ivanovich), 1792-1856, Halsted, George Bruce, 1853-1922, Lobachevskiĭ, N. I. (Nikolaĭ Ivanovich), 1792-1856. Geometrische Untersuchungen zur Theorie der Parallellinien English · Chicago [etc.] Open Court Publishing Company · leaf 40
ndary-triangles, that is proved in the ordinary geometry for therectilineal triangle. 35. In what follows, we will designate the size of a line by a letterwith an accent added, e. g. x, in order to indicate that this has a rela„tion to that of another line, which is represented by the same… … Fig, 28.angles opposite them are BAC = n{a), ABC = fftf). 36 THEORY OF PARALLELS. At the point A erect the line A A at right angles to the plane of thetriangle ABC, and from the points B and C draw BB and CC paralleltoAA. The planes in which these three parallels lie make with each otherthe angles:…
Geometry, Non-Euclidean
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