lo^ DE RESOLVTIONE 



Fx quarum aequntionum vtmuis, qiiaeri pofTct A-C, 

 ob cogiiitum anguluni B et A -f-C — 360°— B - U; 

 \crum quum hae formuiae fatis fint complicatas , 

 rnultiplicLtur prior pcr fin. 5 (A + C) et polleriot 

 per cof. ~ (A + C) et lumatur eoium fumiivj, tum- 

 quc trit : 



(a d-bc-\-{(ib-ac)coCB) fin. .:(A + C)cor. ;(A - C) 

 ■^(bd-a c) 11 n 13. cof. i (A + C jcof. , (A — C) 



+ (fl</-fi'^ + (i'^+tff)corB)cof.i(A-f C)nn.;(A-C) 

 -(^^+cr^-)fiii.Bfin. ;(A+C;fia.KA-C;3io. 



Vbi fi obfcructur cfTe 



fjn.,(A+C)zifin.KC+D) et corUA+C}--cof.'(B+D) 

 tumque 

 {S~ffc''col B "in.,l(A+C)+fin.Bcor. i(A+C')— (fl'^'-/70fin.;-(D-B) 

 {db^ac (co; B.col.5(A+C)-fin.B. fin.UA+C))--(tfH-tfi-.col.;(i;-B) 

 fitt cn|.;(A-C)(;a^-^f)fii.KB + D) + (/^i-fl(,-;fin.i(D-B)) — 

 fiii.;(.\-C)((«^+^Ocor.^(B+D) + (/>pr/+rtOcof UD-B)), fea 

 _ (r.<^- ^c-)fin .i(B+D) + (^^- ^Onn. 'q^-B) 

 1 an^. i ( A + C) _ (:^'^,.)co[.i(B+D)+(6^+af)cof ^D-B) ' 

 Cacterum haec forinula rr.ulto ficilius inucniri pot- 

 cfi , diicendo diagonalem A C quadi iljteri A B C D, 

 nam fi d fFcrentui angulorum B C A, B AC indicc- 

 Tali T. ti,!- p; r ]vi i;t: difTerenti.i angulorum D C A, C A D 

 *'^- * pcr N, erit 1 (A - C) -- 1 (M + N) hinc 



Tang. ■, M + Tang. i N 

 Tang. i (A— C) — n, -^r 7-7- > 



conftat aurem cffe 

 Tang. : xM zz Tang. ; B ; " J' et Tang. ' N z: Taog. L D. ^-^^ ; hinc 



Tang. 



