*"¥.^ ) 348 ( 3-?S<- 



Porro ob angulum 



A C ^ zr A C B - B C ^, et fin. B C A —^^'- , 



' Jm, b C ' 



coJJigitur fatis prope 



B C ^ —^' B b.fln. B ( g — a' )fm. B 



/jn. BC //rt. BC jin.SL' ' 



tumque fiet C g — (^' - ^) cof. A C ^ ; deinde fi C <: non 

 tam fit exiguus , vt arcus b c ipfi b g proxime aequalis 

 haberi queat, fimilis corrediuncula heic adhibenda eft, ac 

 fupra dum differentia ipforum B C, ^ C quaerebatur. Cae- 

 terum quia ang. AC^ — ACB — BC^, erit proxime: 

 cof. A C ^ = cof A C B -i- X. B C Z». fin. A C B, hinc 

 cof A C ^ = cof C -h X (a - fl) ^^^^f^c- ' ideoque 

 CgrrC^cof AC^:r(^'-^)cof C + X(^'-^)(a-a9^i2:|i^--C, 



denique fiet 



b c-b g=-K{b'-bf fin. C* cot. c , 

 ideoque habebimus 



C B - f ^ 3= C B - C ^ + C ^ - C ^ -f- C ^ - ^ g-i-^ 5 

 — c b — {a — a') cof B — 5 X (a— «')' fin. B* cot. c 

 4- X (« - a') {b - b')(^^'^ -1- {b - b') cof C 

 -U(^-^')'fin. C^cot. f , 

 quae formula certe pro adco exadia haberi poteft, vt omni 

 in cafu, fahem nifi arcus c — B C valde euadat paruus, ad- 

 hiberi queat; fin vero fit c — 90° , exade erit 



CB- cb=:{a-a>) cof.B -\- {b - b') coC. C. 



§. 8. Ex confideratione triangulorum ACB, Ar^, 



deduximus 



cof c — cof a cof b -f- fin. a fin. b cof a et 

 cof c' — cof a' cof b' -\- fin. a' fiu. b' cof a, 



vnde colligitur 



(cof e — cof a cof b) fin. a' fin. b'- (cof c'—co(.a' cof.b')Cin.afii\.b. 



Vt 



