ADDITION AND SUBTRACTION OF VECTORS 435 



then P = \/X*+ Y'+Z* 



i X 

 a = cos" 1 



P 



ft = cos- 1 X 

 P 



,Z 



V = COS" 1 



P 



Example. A, B, and C are three vectors whose magnitudes and 

 directions in space are given in the table below. Find A + B + C 

 and A - B + C. 



(1) To find A f B + C 



X = 4-330 + 1-6904 + 4-2426 

 = 10-263 



Y = 1-7100 + 3-3920 + 2-7240 

 = 7-8260 



Z = 1-8240 + 1-2800 + 3-2526 

 = 6-3566 



p= VlO-263 2 + 7-8260 2 + 6-3S66 2 

 = 14-38 



