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 167
the chord of the arch is a mean propor-tional between the diatneter and a line which is the dif-ference between the radius and the foresaid perpendicularfrom the centre. Let ADB t)e a circle, of which the centre is C; DBE any arch,ftn<l DB the half of if; let the chords DE, DB he drawn ; as also… … OF GEOMETRY. BOOK I. ler BD a mean proportional between AB and BF, the excess of the ra-dius a)i»ve CF. Join AO; ami because ADB is a riajht angle, bein^ an ansjle in asemicircle: and because CGB is also a ris^ht -.ngle, the trianglesABO, CBG are e<|uiangi!ir, anil, AB ; AD .. BC : CG (4. 6.),…
Euclid's Elements · Geometry · Trigonometry
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