•*S»I ) 184- ( 3-?l<- 



lam (A) fieri minimum ponatur, fi 



J -^ {d X- -i- d y) •'V ' 



fuerit minimum. Quare fit Y funiflio ipfius y, dX-^'dyy 

 ex aequatione lineae B F eruenda, atque fubflituenda lo- 

 co z in formula integrali, et pofito dy —p d x ^ trans- 

 formabitur illa in hanc: 



fi^zdx)^ r^-^,\r-:^y/\ 



Erit itaque 



inxta Variationum methodum. Quare 



M — p + p' s' -^ p^ -h p' v N — o P — g 4 - X- Y , 



Cumque Aequatio lineae quaefitae determinari debeat ex 

 aequatione N — j-| = o , erit manifefto ^ P — o , ideoquc 



P = (T^^fyl^, = conft,A. 



Quapropter 



fl H- * - Y =r A (i -^ /)') y (r + p»), 



(« + .v~YrrrA'(i+p% 



(a + jf-Y)»=' = A* = ^(i+p'), 



(a -i- .V - Y)*^» - A*'^ =: A^ = 'p% 



(fl-f-A--xr'"-A^ 



A'- = ' 



— p^— — ^ . Erpo 



dr — dx\Q 



d X 



la-\-x-YY--'' -A'--' 



A' 



y((«+-.v-Y/---^-A*=^), 



) 



p = 



