= (8) 



§. io. Confideretur primo progreffio ifta cofinuum, 

 quorum anguli in progreffione arithmetica progrediantur et quo- 

 rum numerus fit n : 



t~ cof. (a-f-2j3)-f-cof. (a-f-4(3)-+-cof. (a-+-6(3)-+- ..... 



. . . . -+-cof. (a-+-2»(3). 



Iam multiplicemus vtrinque per 2 fin. |3, et cum fit 



2 fin. (3 cof.. y — fin. ( (3 -f- y ) — fin. (y — |3 ) , 



proueniet fequens forma: 



2/fin.j3=— fin.(a-f-|3)-f-fin.(a-f-3(3)-f-fin.(a-f-5(3)-f- ...... 



fin.(a-f-(2«n-i)(3) 



— fin.(a-f-3(3) — fin.(a-f-5 (3)— . . . . 



vbi omnes termini intermedii manifefto fe deftruunt, ita vt foli 

 extremi remaneant, hincque ergo fiet 



t /ni- [ a -+- ( 2 n -4- i ) J3] — jin. I a -+- (3 ) 



§. ii. Deinde vero iidem cofinus combinentur cum 

 numeris naturalibus i, 2, 3, 4, «, ac ftatuatur 



u~ 1 cof. (a-+-2(3)-+-2cof. (a-f-4j3)-f-3Cof.(a-f-6(3)-f- . . . 



-+-«cof.(a-f-2«p) 



qua exprefllone dutfa in 2 fin. j3, adhibita refolutione qua modo 

 fumus vfi, confequemur 



2«fin.|3-— fin.(a-+-p)-+-fin.(a-f-3(3)-f-2fin.(a-4-5P)-f-. . . 



-+-fin.(a-+-(2«-f-i)|3) 



— 2 fin . (a -f- 3 13 ) — 3 fin . (a -+- 5 p) 

 quae forma reducitur ad iftam: 



n fin. (a -+- (2 n -+- 1 ) |3) — 2 u fin. (3 = fin. (a -+- (3) -+- fin . (a-f-3 p)-f-- 



-+-fin.(a-f-(2« — i)(3) 



quae vocetur zz v. 



§. 12, 



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