Space and geometry in the light of physiological, psychological and physical inquiry (1906)
Mach, Ernst, 1838-1916, McCormack, Thomas Joseph, 1865-1932 · Chicago The Open court publishing company; [etc., etc.] · leaf 125
a line CD (Fig. 17) join the two extremi-ties of the equal perpendiculars erected on a straightline AB, and the perpendicular dropped on AB fromany point N of the first line, viz., NM, be equal toCA = DB, then is the hypothesis of the right angledemonstrated to be correct. Saccheri rightly doesnot… … Fig. 18. Fig. 19. shortest line on a sphere and the two faces of whichcannot be made congruent. Other experimental proofs of the correctness ofthe hypothesis of the right angle are the following.If the angle in a semicircle (Fig. 18) is shown to bea right angle, a -\- fl = R} then is 2a + 2/? =…
Geometry -- Foundations · Space perception
Internet Archive · Gerstein Library, University of Toronto · Public Domain Mark 1.0. Free to use for anything.
