fin. A G n: fui. A C . fin. A C G; 

 fm. D F zz fm. A C fin. D C F , 



proinde 



fin. A G' -h fin. D F^ =: fm. A C% ob 



fin. A C G= = cof. D t F'. 



§. 4. Theorema III, Eadem adhlbita coujlru&io- 

 ne ejl 



2 fin. I A B . fm. i B D =1 fin. B E . fm. A C. 

 Demonjlr. Nam ob 



fm. A G = fin. A C . fm. A C G et 



fm. D F = fm. A C . fm. D C F , fit 



fm.AG.fm.AC = fm.AC^fm.ACG.conACG,- 

 et quiin:! fit 



2 fin. A C G . cof. A C G z= fin. A C B, ob 



A C B := 2 A C G, crit 

 2 fin. AG . fin. AC =: fin. AC^ . fin. A C B = fin. AC . fin. BE , 

 cx quo liqnet propofitum. 



§. 5. Tlieorema IV. Jisdem pojiiis erit 

 tang. A E . tang. A C rr tang. A B tang. \ A B 

 Vemonjlr. Sf^-?- = cof. G A C ; fimiliquc ratione 

 J^i^l- rz cof. G A C , erit ergo 



tang. A B ;' 



tang. A E . tnng. A C ir: tang. A B . tang. A G 

 =: tang. A B . tang. i A B. 



