-.1 



( \l> KB 





theee have one variable, s. in com moo. Equating the values of 

 eommon variable from the two equations, gives 



. may be written, to correspond with equations [26], 



1 Mi 



*, although the denominators 1, - . | of equation (4) are not 

 direction cosine* of any line, yet, by equations [5], they differ from 

 men direction cosine* only by the diviaor 



VI + | + H - 



Rewriting equation* (4) in the form 



Viui Viol viol 



ond* entirely to equation* [26]. Therefore the line 



he point (1, 1, 0), and it* direction angle* are given by the 



relations 



7SS 



The method given above i* evidently perfectly general. 



Viol' * y ~ viol 



224. The angle between two lines ; between a plane and a 

 line. If the equations of t\v< straight lines be written in the 

 lonn 



thi-n by Art. 228, II, tlu-ir direction 



"-": 



(3) 



