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Show FORMULA}. ING. A MANUAL OF LAND SURVEY IV c the section 79.63, one-fourth of which is 19.903. Hence rate of 20.055 - line and half-quarter-line converge at the the table of 19.9075 = .1475 chains per mile. From to be a little departures we find the corresponding angle SecA c- b =-=secB ' a cosecA ' ‘ Vers A = -_- = covers B c c-- a coversin A = -= _vers. B_ c greater Hence we make the angle gab 6' more than 6'. rdingly. than acd = 89° 30+', and run the line acco of many labor- The foregoing are given as samples young surveyor saving uses of the tables, which the avail himself of‘ should study out and. be prompt to when the occasion requires. AND FORMULJE. TRIGONOMETRIG FUNCTIONS K ' H , Exsec A = -b- = cocxsec B the various trigonometric functions. Let ABC "em. -. ' represent the angles, and abc the sides opposite in the right triangle formed by the radius, sine and cosine. Other parts as shown in the figure. .A coexsec A =_--- = exsec B . a, ccosAzacotA IcsinAzbtanA ccosB=bcotB a: b: a, b I sinA_cosA c :4 csinszatanB 1/<c_+'a> (c' - a! u/(c + b) (c e 6) Let Fig. 83 represent G c~ a 0-- !) ' 0:9O°=A+B- b a ab : sin B cos B Area = '2" U/az + 02 c, CL, : [1 4 . 0- xiv; Jf \ f" o FIG. 83. Then sin A =B0' cos A = A0 tan‘A =DF cot A =HG = AD sec A versin A =. CF exsec A = BD chord A = BF c b = __-.---, cotA --cotB .= AG cosec A coversin A = BK coexsec A = 136‘ chord 2 A = 2 BC. Useful in measuring cot A . = =sinB H cot B . cosA H cosB ale-'Qlo-I ll TanA == SinA ll = ala calculated with radius Tables of these functions are , AH == 1. c-Ia 4-?4: c . = - =cosecB b tan B "heights of objects or passing obstacleszin line. , |
