Ball, W. W. Rouse (Walter William Rouse), 1850-1925 · London, Macmillan and Co., limited · leaf 343
319 CH. XIII] THE PARALLEL POSTULATE of a will be changed but the triangle, and therefore A, will not be altered. Hence A cannot depend on the value of a; accordingly it must depend only on £ and C, D … Now take a right-angled triangle DEF ’, of which D is the right angle. Draw EG perpendicular to EF. The angle EDG in the triangle EDG is calculated from the other two angles of that triangle, namely E and a right angle, in the same way as the angle F in the triangle DEF is calculated from the other…
Geometry · Astrology · Space and time · Matter · Magic squares · Mathematical recreations
Internet Archive · University of Illinois Urbana-Champaign · Public domain (published before 1931). Free to use for anything.
