7* 



f. 2'-$. €mh nurtd fit d% — dv>fcov§ *-- V — i sin3-\ for- 

 * raMvend^ erit pJ^M^^^J^^%m } quamobren* 

 pro reMurione quaefita erit v ' 



fPdv =z pjL c ^J^rJ^ et /Qdv — /^illlLzi^, 



■/s V s 



quarum ergo formularum integralia inveftigari oportet. 

 Evidens autern eft hinc angulum gj neutiquam comrnode 

 per v expnmi pofse. Etsi enim tang3w — — -—!*—, hic 



trifectione anguli opus fbret, unde formulae noftrae plane 

 inextricabiles prodirent. 



§. 16. Maxime igitur memorabile eft, has ambas for- 

 rnulas integrales in quibus eft s — y (1 -+- zv 3 cos9- -+■ v 6 ) et 

 tang 3 -bi — _J£ij_yt_ , quas vix ac ne vix quidem per 

 folam v referre liceret , nihilominus per logarithmos et 

 arcus circulares integrari posse. Facile autem intelligitur 

 per idoneam fubftitutionem loco v ^liam variabilem idoneam 

 in calculum introduci debere, cujus ope hae formulae fim- 

 pliciores reddi queant, id quod commodifsime fieri pofse vi- 

 detur , si loco v angulus Cj) introducatur, ita utfit<p=3-~ w, 

 unde ftatim oritui fPdtfZzfhjBM et/Qdvzzzf^-f 1 *, ubi 



Vs Vs 



ergo litteras v et s per (J) exprimi oportet. 



§. 27. Cum fittang 3_ zz: JE?Jj±l$ fi hunc angulum 3<*> 



? ' O ° 1 ■ t3 cos 3i ' & 



introducamus.eiit tPf^-^-^JliJJJL^, nnde ob 3$— 3_ = 3$ 

 elicitur tang 3 $ - _i5Jl__, 3 unde reperimus i; 3 -. cos 3S -^^ 

 Hinc fumtis quadratis erit 



v + 1 v* cos 3 S -+. cos 3S 2 _= sin 3 S> ^|?. 

 Adefatur titrinque sin 3-9-* eritque 



»'■+■ 2i; 3 cos 3 » ■+ 1 = tt 2= ^-1-! , ideoque tf ==: £*L 3 » 



sjh 3<+> 2 ^ «713$ 



Hacte- 



