PHYSICAS E NATURAES 



41 



XI 



1 a-^-b-^-c a-\-h-\-c a-\-ò-\-c 



O a a-{'b -\- c a-\-b -\- c 



O a-{'b-{-c b a-\-b-\-c 



O a -{-b -{- c a -\- b-\-c c 



= 4p(Rr-\-2p'^); 



XII 



= 1 — 2(jp2_r2_4i?r); 



XIII 



r2 — 3_p2^4i?r' 



XIV 



=p^ -\- r (r -\- á R r) ', 



XV 



2 1 

 ,. 1 



c^ — 



1 

 1 

 1 



62 



= SErp^; 



