-441 ) 291 C l?2<- 



§. 13. In fiiperioribus fuppofuimus effe b—b' — a, 

 Quod fi vero rationem quoque habere velimus difcrepaa- 

 tiae, quae inter hos arcus intcrcedit, inueftigatio anguli 

 « -f- a' fequenti ratione expedienda eft: Ob 



.cof. {■f—c)—'coi'.b coC.e -f- fin. ^ fin. e cof. (^ — a), 



cof. (/+ c) = cof.h' cof e 4- fin.^' fin.^ cof. « + a'), 



fi prior aequatio miiltiplicetur per fin. ^', pofterior per 

 fin. ^, earumque differentia capiatur, erit 



cof. (/- c) fin. b' - cof. (/+ c) Cw.b m cof. e fin. (b' - b) 



-f- fifi.^. fin..^'fin. ^. (cof.,((^ — a) — cof..(^+a')), 



hincque 



ci; f.(f~c\fm.l' — co S. (fH- c^ ftTub — cof. e. fin. {.V — 5) 

 fin.b' Jin.b Jin.e 



=1:2 fin. i (a' + a) fin. (<^ -f «lrz_«), fiue 

 cof./. cof c. (fin. ^'- fin.'^) -\-iin.f. fin. r(fin. ^. + fin.^) 

 — cc>ff.fin.(^'— ^)— 2fin.(^'fini^fin.f.fin.(*-^jf]n.C/~f.(^l:i5)\ 

 Tumque 6b 



fin. 6' -'fin. * ='2 fin. [ [b' - b) cof \ (b' -f .^), 

 fin.^' 4- fin..^ - 2 fin. l [b' + b) cof. '- [b' — b)y 

 Sin.{b' - b) — :2. fin. ■ (^'-^) cof l {b' -bjy 

 coHigitur 



fin. / fin. c. fin. *.1±1* cof. t:± 



+ cof /crif. c fin. *lzicof. ^* -cof f» fin.^* cof *-ln* 

 = fin. 6'. fin. b. fin. f.fin. »lft3, fin. «4-^«) ; 

 ex qua fornwla, fi pon^tur 



^-a, cof ^^ - I et fin. (< -}- ^^«) - fiiK ^, 

 prodibit 



O o 2 fin. 



