New plane and spherical trigonometry, surveying, and navigation (1903)
Wentworth, G. A. (George Albert), 1835-1906 · Boston : Ginn & Company · leaf 137
atthe length of the staff is 2 a cot 2 A. Let h = height of tower, and I = length of staff. Then h = a tan A. h + I = a cot A. I = a (cot A — tan ^1) cot2 A - 1 = a — cot A = 2acot2A. 26. A line of true level is a lineevery point of which is equally dis-tant from the centre of the earth.A line… … Given CA = 1 mile, BC = radiusof the earth = 3956.2 miles; requiredAA = AB- CB. The required distance is much toosmall to be obtained by the usualprocess of solution. It is most easilyfound as follows: AX)2 = AB2 - BC2 = (AB-BC)(AB+BC). .AB-BC=- ACZ AB+ BC Now, as AB differs very littlefrom BC, and…
Trigonometry · Surveying · Navigation
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