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 240
SPHERICAL TRIGONOMETRY. 239 PROP. III. If the pole of a great circle be the same with the inter-section of other two great circles; the arch of the first-mentioned circle intercepted between the other two, isthe measure of the spherical angle which the same twocircles make with one another. Let the…
Euclid's Elements · Geometry · Trigonometry
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