J-1 -JJJ ' 







.ill 1.ISM8 



H1 



These are the aaooud atamlurtl . .0 equation of a 



) The ttrtriyht //< trtVA jrt'0** Irate* on th* oofirdinaU 

 planet. One of the aitnpleiit set of planes for determining a 

 straight line is a pair of plane* through the line and perpen- 



lar respectively to the coordinate planes (it 

 Then the equation of these planes will be the same as the 

 equations of the traces of the line on the corresponding cofir- 

 dinate planes (A Thus, if the equation of the traces 



of a given line upon the sav and ys-plaues are, respectively, 



[88] 



then, considered an simultaneous, these are also the equa- 



tions of the given line in 



space. 



In Fi. 10 given 



traces are ABL' in the 

 wvplane, and CDN 1 in the 

 yf-plano P is any point 

 inthegi .-^htline, 



and Q,Jl>S*re the points 

 where the line pierces the 

 y-, yi-, sivplanes, respeo- 

 Tlirn it is clear 

 that in I'nuutiuiis [28] 



i A OK. 



Also, since, by equations 



OA - - ^, AR 



,i- 



