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 76
e of the angle BAC. First, let D, the centre of the circle, be withifi the angle BAC, andjoin AD, and produce it to E: Because DA is equal to l)B,the angleDAB is equal (5. 1.) to the angle DBA;therefore the angles DAB, DBA togetherare double of the angle DAB; but the an-fijle BDE is equal (32. 1.)… … A gain let D, the centre of the circle,be without the angle BAC; and join ADand produce it to E. It may be demon-strated, as in the first case, that the an-gle EDC is double of the angle DAC,and that EDB a part of the first, is dou- ^ vble of DAB, a part of the other; there- \fore the remaining…
Euclid's Elements · Geometry · Trigonometry
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