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 75
DE;and because FGC is a right an!2^1e,GCF must be (17.1.) an acute an-gle ; and to the greater angle tlie great- xer (19. 1.) side is opposite: ThereforeFC is greater than BG ; butFC is equalto FB; therefore FB is greater than FG,the less than tlie greater, which is im-possible; wbeiefore FG is not… … Becansfi; PROP. XIX. THEOR. If a straight line touch a circle, and from the point ofcontact a straight line be drawn at right angles to thetouching line, the centre of the circle is in that line. Let the straight line DE touch the circle ABC, in C, and from Clet CA be drawn at right angles to DE;…
Euclid's Elements · Geometry · Trigonometry
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![An illustration from Nicolai Copernici Torinensis De reuolutionibus orbium coelestium, libri VI : Habes in hoc opere iam recens nato, & aedito, studiose lector, motus stellarum, tam fixarum, quàm erraticarum, cum ex ueteribus, tum etiam ex recentibus obseruationibus restitutos: & nouis insuper ac admirabilibus hypothesibus ornatos. Habes etiam tabulas expeditissimas, ex quibus eosdem ad quoduis tempus quàm facillime caculare poteris. Igitur eme, lege, fruere. [Line in Greek] (1543)](https://img.insideoutlibrary.com/img/200/ia-nicolaicopernici00cope-332-223.webp)
