CHAPTER V. 



FORCES IN DIFFERENT PLANES. 



To Jin' mltant of 



'er of parallel forces acting on a / 

 determine the centre of parallel forces. 



Let the points of application of the forces be referred 

 system of rectangular co-ordinate axes. Let m iy w 2 ,... be the 



points of application; let x v , y l9 z lt be the co-ordinates of 

 the first point, # 8 , y a , z t those of t! nd so on ; let 



/',. /',,.. .be the forces acting at these points, those 1 

 reckoned positive which act in tin- diivctin of P tt and those 

 negative which act in the opposite direction. 



Join T/^m, ; and take the point m on m^ such that 



P 



