fin. i (A + B) r= Cm.lA cof.| B 4- cof. a A fin. ■ B 



— (/;.7. (? - i) -I- /;n..{t - a)) yfin. s . J in. (s - c) 

 Jin, c Jin. a Jin. b ' 



vnde deniio concluditur 



cof.i(A-|-B-}-C}~cof.i(A4-B)cof.iC-nn.J(A+B)fin.iC 

 — ^Sp^f^lz^ y(nn. j . fin. {s~ a) fin. is-b) fin. (j-0) 



jin.a jin.b jKi.c v v / \ ; \ /'/ 



-^^'"\'~^;'^{'"-''-^'Vlfin.jfin.(.f-g)fin.(j-Z>}an.(^-Ol 



Atqui 



fin j - fin. {s - c) — 2 fin. ^ c cof. ] (a + ^) et 



fin. {s — b) -{■ fin. [j- — fl) = 2 fin. [ c cof. ^ ((7 — ^) , 

 quorum diffcrentia erit 



2 fin. t c (cof. t (^ + ^) - cof. U« - ^) ) 

 zi: — 4 fin. ; i^ fin. ; a fin. ^ ^). 



Hoc igitur \alore fubftituto erit: 



V(fin.j fin.fj--fl) fin. {s—b) fin.fi-c)) 



cof.HA+B4-C)z= 



2. COl. i <? COl. i /> COl. j C 



§. 14. Ex aequatione 

 cof. A zz fin. B fin. C cof. a - cof. B cof C, 

 fi fimul addntur ct fubtrahatnr fin. B fin. C, colligimus 

 cof. A n: fin. B fin. C (i + rof a^ - cof (B - C) 

 =: 2 cof ; a' firi B fin. C - co(. (A - C) ; 



cof. A — - fin. B fin. C (i - cof a) - cof (B + ( > 

 = - a fin. i a' fin. B fin. C - cof (B + C)i 

 vnde dcducimus: 



— fin„ 



