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 439
to determine the position ofthe segments. This can be done by the signs of the proportion tan i {s — s). … Fig. 56. tan i (s + s) : tan ^ {a + b) : : tan i {a — b) 1st. Tan ^{s + «) is always +, since, if D falls in the base, 8 + s < 180°;and if D falls without, by taking the nearer perpendicular, « + & is still < 180°(132). .: H« + «) < 90°, and tan H« + *) is +. 2d. When a + b < 180°,…
Geometry · Trigonometry
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