) 77 ( 



$. 24» Theorema XVIIT. 'Eadem fa&a conftru" 

 Stione ejl 



tang. E C =1 ^~ ^Q^-^ ^Q^ (^- A) cor. (S-B) cof . (S-C) 



2 cof. i A col. \ B cof. i G 

 Demonjlr. Quum fit per §.14 



fin j r: "^-^o^-Scor.CS-A^cof.CS-B^ cof.^S-C) 

 "" 2fin.; Afin. tBfin.iC * 



atque in Theoremate praecedente 



tang. E C :z: tang. i A tang. l B tang. ^ C fin. /, 

 fiet omino 



. p p _ ■/- cof S cor. (S-A)cof.(S-B ) corfS-C) 



tang. h, u _ n~of \ A cof -; B cofrTC * 



Idem vero fic quoque facilius demonftratur: 



tang. E C n fin. A E tang. E A C :=: fin. (j — «) tang. | A , 



at per §. 13 efl: 



y-cof Scof.(S-A)co r.(S-B)cof (S-C) 

 (-^ ^) — j^cof. 4 B CQl. i C fin. i A ' 



vnde Hquet propofitum. 



§. 25. Hinc etiam formulae fuppetunt pro arcu- 

 bus AC, BC, DC ct angulis ACE, BCE, D C F, 

 fcilicet in triangulo E A C eft 



tang. A C z= "^^ =: 1^0^^ 

 ^ col. EAC cof.iA 



at per §. 12. eft 



cof.iA=:y^;^'; hinc fic 

 tang.ACzzli^^^.J-^. 



K 3 Tum 



