*H P RI N C l P l A 



ficque emci debet , vt fit 

 idxdydz~pqsi:<p(T-hprs'K^<7+qrs(P^(T-pqr'n(p^. 

 Cum autem huiusmodi prisrm bafi fuae inferiori nor- 

 maliter infifht , tres autem altitudines habeat inaequa- 

 les , eius fbliditas reperietur , (i bafis multiplicetur per 

 trientem fummae trium iftarum altitudinum. 



31. Hinc ergo foliditates horum prismatum 

 truncatorum erunt : 



pqs-n<p<TZ=: ±pqs(pTt-\-q<P~\-S(T) 

 prsiz ^crzr \p rs(pTr-\- r % -W<r) 

 ars<Pz<r ~ \qr s(q<p-\-r f-J-jo-) 

 pqr%<P g— \pqr(p n-\-q(p-+-r %}. 



Cum autem fit pqr—pqs-\-prs-\-qrs y erit fum- 

 ma trium priorum prismatum poftremo minuta, fiue 



\dxdydz--\pn.qrs-\q<p.prs--\r^.pqs^-\s<r.pqr\ 

 fiue 



axdjdzzzzpqr. '(T-^pqs.r^-zprs.q^p-^qrs.pit. 



32. Superelt igitur , vt horum prismaium ba- 

 fes definiantnr : verum antequam hoc faciamus , pona* 

 mus ad fequentem calculum contrahendum : 



AQ— AP-j-Q;Q^— Vp-\-q,q(p— pn-\-(p 



AR — AP-f-R; RrzzP/>-*-r; r £==p7r-f-g 



A$zzAP-f- S ; "S jzzPp-Ks J<rzz/>7T-f-<r 



atque his poftremis vaioribus fubftitutis , termini pn 

 continentes fe mutuo deftriient, entque 



d 'x dy d szz 2 p q r . <r — 2 p q s . £— 2 p r s .<p 



ficquc 



