" (200) 



%z=i(F g-{-Gf) cof. (0 — F G ~fg. 



Hinc ftibftituto valore pro cof. w fiet 



S—(Fg-i-G/)(F/+Gg-4-H^)-FG-f^-, flue 



5-_FG(i-//-gg)-/g(.t-F"--G^) + H/.(F^-^G/). 

 Quia igitur eft 



I ~ff~ gg=:bh et I — F"- — G"" = H% fiet 



5 — H /7 (F g- -j- G/) — F G ^ ^ — f ,e H H , 



quod manifcllo efl: producT:um ex fnfloribus Gh — H^ et 



H/ — F /^, ita vt fit 



5 = (G/p — H^-)(H/— F/.). 

 Quod fi iam vno gradu progrediamur, hinc deducimus valorem 



&z=(llf~Fb){Fg~Gf) 

 ac denuo progrediendo 



^z:^iFg—Gf)iGh-Ug). 



§. 23. His igitur colligendis fequcntcm aequationem 

 nancifcemur: 



m?f2Cin.(j^' = (Gh-Ugyaa-^2(Gh~Ug)(Uf~Fh)ab 



(Uf-Fhyhh-^2(Uf-Fh)(Fg~Gf)b(; 



(Fg-Gfyc-c-i-2(Fg-Gf)(Gh-Ug)ac 



quae exprefiio manifedo efl: quadratum. Extrada crgo radi- 

 ce orietur: 



»/fin.co — (G/'-H^)^-+-(H/-F/7)^-f-(F^-G/)r 

 quae formula ctiam ncgatiue potuiiTet accipi , fed quia de di- 

 ftantia fermo efl. ea fcmper pofitiua intclligi folet. Quin etiam 

 fin. co negatiue fumi poflet, quia tantum inclinationis cofinum 

 immediate inueniuais, vnde vna ambiguitas ab altera tolii eft 

 cenfenda. 



Pro- 



