Elements of geometry : containing the first six books of Euclid, with a supplement on the quadrature of the circle, and the geometry of solids : to which are added, Elements of plane and spherical geometry (1826)
Playfair, John, 1748-1819, Euclid · Philadelphia : Marot & Walter · leaf 299
rallel by hypothesis, and therefore the anglesAGH, GHD are not unequal, that is, they are equal to one another. Noxv the angle AGH is equal to EGB, because these are vertical,and if has also been shewn to be equal to GHD, therefore EGB andGHD are equal. Lastly, to each of the equal angles EGB, GHD… … The following proposition is placed here, because it is more con-nected with the First Book than with any other. It jsuselul for ex-plaining the nature of Hadleys sextant; and though involve«l in theexplanations usually given of that instrument, it has not I beliove,been hitherto consiilered as a…
Euclid's Elements · Geometry · Trigonometry
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