258 



NEW MODE OF REPRESENTING 



=r .r, when cc > a and less than h ; and Y ~ 1- 

 when X > h, consequently f(.r) = ; f,(cr) = x ; 



( a — x\ ( h — .v\x . { ^ h — x\ 



b <t> X 2x^ 



This equation will determine the attraction 

 upon a point .r, wherever it may be situated. 



Required the equation to the system of lines in 

 the trapezium ABCD. 



(17). Let the 

 origin of co-ordi- 

 nates be at A. 

 Put AE — a and 



And let, 



If = e X, be the equation to the line AB, 

 y = a e, do. do. BC, 



V =/(.' - a), do. do. CD, 



