Legendre, A. M. (Adrien Marie), 1752-1833, Brewster, David, Sir, 1781-1868, Davies, Charles, 1798-1876 · New York, Wiley & Long · leaf 54
when their angles are so,but are in all respects proportional to their angles : hence, twosectors ACB, ACD, taken in the same circle, or in equal circles,are to each other as the arcs AB, AD, the bases of those sectors.It is hence evident .nat the arcs of the circle, which serve as ameasure of the… … Let BAD be an inscribed angle, and letus first suppose that the centre of the cir-cle lies within the angle BAD. Draw thediameter AE, and the radii CB, CD. The angle BCE, being exterior to thetriangle ABC, is equal to the sum of thetwo interior angles CAB, ABC (Book I.Prop. XXV. Cor. 6.) : but the…
Trigonometry · Geometry
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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-66-43.webp)
