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
join CF.DE touches the circle ABC, and FC isdrawn from the centre to the point ofcontact, FC is perpendicular (13. 3.) toDE; therefore FCE is a right angle:But ACE is also a right angle; thereforethe angle FCE is equal to the angleACE, the less to the greater, which is im-possible : Wherefore F is… … OF GKOMETRY. BOOK III. PROP. XX. THEOR. The angle at the centre of a circle is double of the an-gle at the circumference, upop the same base, that is, uponihe same point of the circumference. Let ABC be a circle, and BDC an angle at the centre and B AC anana;le at the circumference, which have the…
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-162-91.webp)
