Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn & company · leaf 93
Fig. G6 In Parallel Sailing a vessel is supposed to sail due east ordue west. The distance sailed is the departure made; andthe difference of longitude is found as follows: 116. Given the departure between any two meridians atany latitude; find the difference of longitude of any point onone… … In rt. A ODA, Z A OD = 90DA lat. Hence, OA = sin (90° — lat.) = cos lat. The A DAB and OEQ are similar. Therefore, DA AB OEHence, cos lat. Therefore, EQ =That is EQAB eq AB DA or OA ABEQ = AB xsecl&t. cos lat.Diff. long. = depart, x sec lat. 117. A ship in latitude 42° 16 K, longitude 72° 16…
Trigonometry · Surveying · Navigation
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