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 249
ig. 342. * This should be executed on a sphere. Few students get clear ideas of polar triangleswithout it. Care should be taken to construct a variety of trianp^Ies as the given triangle,since the polar triangle does not always lie in the position indicated in the figure here given.Let the given… … Fig. ai3. PROPOSITION XXIY. o96» Tlieorem,—Amj axgle of a spherical triangle is thesvppJement of the side opposite in its polar triangle ; and any sideis the supplement of the angm: opposite in the polar triangle. Dem.—Let ABC and ABC be two spherical tri-angles polar to each other; and let the…
Geometry · Trigonometry
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