CHAP, v.] EXAMPLES OF IRREGULAR PLOTTING 135 



The necessary angles and true bearings having been obtained 



at A, B and D, 



(1) Calculate true bearing and distance of B from A and 

 A from B [see (1) in Example I.]. 



(2) Assume A D= 10,000 units. 



(3) In A A D C, given Z ^ C A D, A D C, and A D, find D C. 



(4) In A C D B, given Z « C D B, D B C, and D C, find D B. 



(5) In A A D B, given A D, D B, and Z A D B, find Z« 

 DAB, DBA. 



We have now sufficient data for plotting the points A, B, C 



and D. 



Fig. 27 



Fig. 26 



Example lY.—Tivo inaccessible objects visible from three 'posi- 

 tions which are invisible from each other. 



In Fig. 27, G, 0, W are three stations lying more or less in 

 a meridional direction, but invisible from each other, the 

 latitudes of which have been accurately determined, and from 

 each of which true bearings of the high inaccessible peaks 

 B and P have been observed. 



G m and W n are true meridians passing through G and 



W respectively. 

 Let the observed diff . lat. G m, between G and = a. 

 Let the observed difE. lat. W w, between W and = 6. 

 Let the observed true bearing of B from G, Z B G m = G. 



