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 232
ains to be explained. These tables usually contain the sines, ^c. to every minute of thequadrant from 1 to 90°, and the first thing required to be done, is tocompute the sine of 1, or of the least arch in the tables. 1. If ADB be a circle, of which the centre is C, DB any arch ofthat circle, and… … tional between AH, half the radius, and AF,the line made up of the ra-dius ;ind the perpendicular CF. Now CFis the cosine ol the arch BD,and CG the cosine of the halt ol BD; whence the cosine ol the half ofany arch BD, of a circle of which the radius=l, is a mean propor-tional between i and 1+Cs.…
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-308-201.webp)
