=A s .f s and as r= 



fc-'fcu =*.v*-./ and /=/ c . =1 



D c _ x 



l) f dex 



c : x=h-: (dex) and since ^-=< 



Ai J^c 



fc _ /j . f _ n f de- 



' ' ~ 



Substituting values for / 5 and / 6M in the following : 



fc . ^ / 



we g et /g "f" -y t . b=A s . n ,f c .d f x 



2 x 



and from this t 2 .b 



x=n . A 5 (de)+^T 



t . b+n . A s 



and since xy=. --' c ~^~ 2 ' ^ cu substituting a value for 



3 fc -\-Jcu 

 feu- 



/ 2 



