Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 371
llax,then the nearest planets, and then the sun. Let S (Fig. 39) represent the celestial body, 0 the positionof the observer, C the centre of the earth, and Z the zenith ofthe observer. The geocentric parallax is the angle s = zos - zcs. ZOS is the apparent zenith distance, and ZCS the geo-centric… … Fig. 39 Let P == the parallax in altitude, Z = ZOS, the apparent zenith distance, R= CO, D = CS. CORRECTIONS OF THE OBSERVED ALTITUDE 383 In the triangle COS, sin S sin COS sin P sin Z = , or = -—— • CO CS R I) Hence, sin P = -—-—- • (a) Since P is always a small angle, the arc may be taken forits…
Trigonometry · Surveying · Navigation
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