"3 



ideoque 



r r zzz a & c A et r — ^ a b c d 



(d -+■ c,* a -t- c 



Corollarium i. 



J. 17. Cum igitiir in hoc quadrilatero lit X— ~- c9 

 quaeramus etiam reliqua laterum fegmenta, quae fupra lit- 

 teris /, g, ' h, i, infigniuinius, ac reperiemus 



g — a — x — J±- 9 



o a H-c 5 



h — b — a-\- X — - 



c 



i — cl — x-= J£iL 



a -f- c ' 



5c 



vnde ftatim intelligitur fore 

 fh— ahcd n ~rr, 



J [a -f- c' 2 * 



• __ j^cd • 



53 (a -t- c}2 * 



Corollarium ?J 

 §. 18. Tnuentis autem his fegmentis /, g, /i, i, tan« 

 gentes dimidiorum angulorum quadrilateri ex $. 7, defumtae 

 ita fe habebunt: 



tang.iA-/^- tang.lBrrT/ii; 



tang. § C = / lf ■; tang. 1 D =V §f, 



vnde fequitur fore 



tang. \ A . tang. J C == i , 

 tang. I B . tang. § D — i , 



confequenter A -h C = 1 8o° et B -f- D ~ 1 8o°, ita vt hoc 

 quadriiaterum finuil circulo fit infcriptibile. 



Nava Ma Acad. Imp. Scient T. X. P Scho- 



