95 DE RESOLVTIONE 



facere Pro noftra autem figiira fiet angulus 



E=:A-Hlini8o°H-BCG 

 ideoque qudm E exlupcrcc iSo°, paiumus 



A -i- B =: I 80° ^ F , 

 jta vt fit F — B C G , eflcque debebit 

 A-h+Wzz 360°- F , hinc 

 B' — 360'- B C G - ^ A B. Ea vero 

 B' =: 360' - ^ B C et B 3: ^ B C , 

 pro pollcriori valore facilc condat efle 



^BC=:BCG4-BADzri8o'-f-BCG-flAB, 

 de priori autem p.itct cfic 



^BO = BC'G-i-BAtf-BCG-|-BA^ 

 ob B C — B C. Idcoqu^ pofito B C G =: F , erit 

 B — I So° -^ F - A ct B' zz 360° - F - A. 



, 13. Problema 12. Datis latevibur a, b, c et 

 fffigulis A , B , inuenii-e angulum D. • 



Ex acquationc quarta ftarim dcJucitur 

 fin. D z= ^ fin. A -f- J- fin. { A -f- B ). 

 Tab. I. vbj jg duplicitate anguli ]) obferuandom, quod fi vniiS 

 '^' ■ eius valor cxprimatur per D>alttrum fnre D'z:i8o-D. 

 Nam fi conflruatur triangulum ABC cuius dantur 

 bina latera kV>-a^V>Q-b et anj^ulus ABCnSo^-B, 

 tumque ducatur rcdla akV) quac cum AB tacit m-\' 

 gulum rtABrr A, inuenictur punclum quadrilatcri D 

 jn interfeclione huius rc(fl.ie cum clrculo centro C 

 radio — ^ defcripto. Suit autcm binae interft^fliones 

 . D, D', cx quo bini valnrcs anguli D prodibuiit, altcr 

 =:CDG, altcr =rCD'G , ell vcro 



CDG+CD'G=:C DG-fC U Az= 1 80. 



14-. 



