30'', ideoqne ^ + ^ — 90 =r 15', 50" rz r , hinc habcbitur 

 ^-1- a':^: 180 , et ^ — a — 167% 12', 39''. 4, exiftente 

 4" =r 170% 57', 58", 9? ex quo coUigitur a' H- a n I 2^ 4.7', 

 20'', 6, et ol' — ct — 5°, 16', 41", <J , ita \'t haec difFcicntia 

 angulorum a', a, anguhim minorem a magnitudine excedat. 

 Manentibus autem valoribus ipforum a et r , fi (3 vltra 

 86°, 26^, 42" augeatur, liquet pro a' nullos valorcs rea- 

 les adferri poflTe. 



§. 21. Praeterea iUi quoque incidunt cafus , vbi 

 neque anguhis a valorem fortitur realcm ; patet autem 

 limitcm valorum reaiium pro a ibi conllituendum , vbi 

 ang. p — 90", hoc eft vbi circulus mrnor, polo P, intcruallo 

 P C) defcriptus, tangit circuhim 2 O in O. Pro hoc au- rp^j^ y^ 

 tem cafu vah)r iinguli OPQ~a, fcquentcm \\\ modum Fi". 4., 

 indagatur. In Triang. Q P n erit cof n Q — fin. N Q — 

 cof. P Q cof P n -+- fin. V Q. fm. P H. cof Q P R — cof OP. 

 cof P n -h fin O P. fin P n. cof. Q P n =r cof O P. fm. O P 

 (i-cofOPQ), ob OP-i-PO — 90^ et OPQ=:i8o 

 ~ Q P n , hinc fiet 



fm. c — fin. 2 a. fin. 5 ct' et fin. \ a- zz £~ . 

 Idem vero et fic demonftratur: 



fin. N Q^fm.O Q. cof PO Qr 2 fin. ^O Q. cof ^O Q.cof POQ, 

 atqui ert 



fin.;OQ=fin.OP.fin.^OPQ. et coflOQng^, 

 tnmque denuo 



'^•-/^r^fin.iPQQ, promde 



fin. N Q = 2 fin. O P. cof O P. fin. ; O P Q'. 



Ma Acad. hnp. Sc. Tom. III. P.I. P p §. 22. 



