Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes and company · leaf 64
. Join these points by the straightlines AC AB, BC. Then, bisect any two of thesestraight lines, as AB, BC, by theperpendiculars OD, OP (Prob. iv);and the point O, where these per-pendiculars intersect each other,will be the centre of the circle. Then with O as a centre, and a radius equal to OA,… … 64 GEOMETRY P ro b 1 e m* . angles OP A and OPB equal, beingright angles; hence, the side OB isequal to OA (Bk. I. Th. iv). In like manner it may be shownthat OC is equal to OB. IJence, acircumference described with theradius OA, will passpoints B and C. through the
Geometry · Plane 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-186-102.webp)
