vnde liquet propofitnm. Si igitnr arcus AD tranfeat per 

 ipfum Polum, quo cafu JACDrrpo", erit tum 

 cof. B C =r cof. I A B cof. ^ B D fin. A B D. 



§. 10. Theorema. IX. lisdem ^ofttis ac in TheO' 

 remate praecedenti erit 



cof. i A C D =3 fin. \ A B fin. 1 B D 



-4- cof. l A B cof. ', B D cof. A B D. 



Bcmonjlr. Ex proprietatibus triangulorum Sphaericorunj 

 B C E, B C F habemus 



fui. B E— fin. B C fin.B C E; 



fin. B F — fin. B C fin, C B Fj 

 hincque 



fin. B E . fin.B F zr fin. B O fin. B C E . fin. C B F 

 -fm.BCE.fin.CBF-cof.BC^fin.BCE.fin.CBF. 

 Et quum fit 



cof EB C - cof.E C fin. B C E zr '"^^^ fin.B-CE, 

 tum.que 



cof.FBC:^^];-|-^.fin.BCF, 

 prodit 



- cof. B C fin. B C E =2 cof. B E cof. E B C et 



cof. B C fin. B C F n: cof B F cof. F B C , 



ideoque 



cof. BC=. fin. BCE.fin, BCF 



— col. B E cof B F cof. F B C cof E B C , 



vnde colligitur: 



fin. B C E . fin. C R F =: fin. B E fin. B F 



cof. B E cof. B F cof. F B C cof E B C. 



Tum 



