A treatise on special or elementary geometry (1877)
Olney, Edward, 1827-1887, Olney, Edward, 1827-1887. Elements of trigonometry, plane and spherical · New York : Sheldon · leaf 449
la:. [NOTE.—This section is designed for such asmake matliematics a specialty. The precedingsections are thought suflScieut for the generalstudent] 14:3, Prop.—In a Sj)herical Tri-angle the cosine of any side is equal tothe product of the cosines of the other twosides, plus the product of the sines… … i Dem.—From Fig. 67, we have,cos a = cos {c — x) cos p cos (c — x) cos b r . = ^: smce cos cos X L cos b cos c cos X + cos b sin c sin x ~~ cos X = COS b cos c + cos b sin c tan x i _ cos b I^ ~ cos X J [expanding.cos (c — x)] ] sm X since = tan x cos a; cos b tan x~ = cos b cos c + sin J sin c cos…
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-319-211.webp)
![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-24-10.webp)
