I ^nzz 



) 79 ( r?C<- 

 I + 2 ^ cof. + ^* — "JL' fln. 4)* 



I -t- 2 f COl. CP + tf' 



(cor.Cl)4-^f 



, pofito 



1 -h 2. e col. (p + f^ 

 »-"-;? = o } fiue f' =: ^. Hinc igitur erit 

 dz.^ -dzV '-^^- _ X^(|)(i4-gcor.(p)- 



Z» T , W '^' *>* y 



(l + 2 ^ COf. Cj) + ^')* 



_ d (| )(i -f - gco f. Cp) = 



y « (i + 2 e cof. (p + g')^ 



▼nde cafus, noftri difTerentialis VI. et VII. deriuantur, dtim 

 pro priori eft n^m, ideoque e <^ i, quod valet pro arcu 

 Elliptico, pro poftcriori autcm efl: tn^^tiy hincque ^ <^ i, 

 quod indic.at arcum Hyperbolicum. 



§. 2o. Deinde differentiale propofitum, ad formanii 



d (p (i -f- g cof. <^Y 



» 

 (iH- 2 ^ cof (p + e'y 



quoque reducetur, ponendo 



^ = vT^ 4-%-tg-|^ev ^"'Je colligitur 



X^(pfin. (p (i +^cof (b) 

 d z z=. - — , — , 



(i 4- 2gcof (pH-^')^ 

 Ijinc facile perfpicitur efle debere 



; V(i-+-se co/.Cp-+-e') '^ •/(>-+- j fcoj. cp _+_«)?» 



ex quo patefcit, ftatui debere Z' zzV ^i —nzz), fiet au- 

 tem tum 



