New plane and spherical trigonometry, surveying, and navigation (1903)
Wentworth, G. A. (George Albert), 1835-1906 · Boston : Ginn & Company · leaf 291
find the local time (apparentsolar time) of sunrise and sunset,and also the azimuth of the sun atthese times (refraction being neg-lected). When and where does thesun rise on the longest day of theyear (at which time d = -f 23° 27)in Boston (I = 42° 21), and what isthe length of the da^ from… … PM=90°-d,ZQ = 90°,PQ = l Then in triangle PMQ, by [40],cos QPM = tan PQ cot PM,or cos t — — tan I tan d. Time of sunrise15 (12 ) oclock A.M. \ 15/ Time of sunset ■(A)- clock P.M. (ii) To find azimuth a = MQ.By [38], cos PM = cos PQ cos QJf,or sin d = cos I cos a. .-. cos a = sin d sec I. (iii) At…
Trigonometry · Surveying · Navigation
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