EIVSQ.VE VARIATIONE. 137 



Eiedo autem elemento dr obtinetur 



dbibr-X g) dq(pr - hq)1 zr fegbj^d!j!^£tegl^5i3a^ 



Qnod fi iam harum binas quasque in locum illarum 

 fubftituamus , calculus haud parum fiet fimplicior 

 hae vero videntur commodiffimae : 



P p-t-qr — " nn(pr-i-q) 



, da(t-r r) __ ( 1 —rr)d?-+-(pp-j-qq-i-2-p.qr)dQ , 



■* "T Prr-qr " nn(pr-+-q) ■ '* 



Vnde affumto q reliqua elementa facile determinan- 

 tur fin autem angulus oj vt cognitus fpectetur, hinc 

 valores pro dp et dr in poftrema aequatione diffe- 

 rentiali fupra data (XVIIL) fubftit-uti determinat-ior 

 nem elementi dq fuppeditabunt. Peruenitur autem 

 ad hanc aequationem : 



dq(pr+-q )fin.u z , x~ , , dCfKp-HjCO/.cok 



y*5jf =(/>r-r-j)fin.(fl(^ca-^g r } 



— n-n4l^q-){^pr-\-q-\-qrr-{p^qr){ i+rr)cof a) 



-^(i-rr)cof w 2 ) 



- Tnwhq-AqiPp-qq^ip-hqrXpp-^-qqyo^ 



+q(pp+qq-\-2pqr)coi.u 2 ). 



XXI. Subftituendo denique hic pro d? et dQ 

 talores fupra indicatos (XVIII.) 



dgfin.ui . dJp(p-+-qcof.w ) 



t~r*l r — ^ipp-rqq) 



•4- i^^F)(7^^2^-^^r4-(p+^r)(3^-/>r)corw 



Z q{pf-q4- 2.qrr)coi.(a 2 ) 



£ <> 3 N X d fl t q(pp-qq)^prWr)(pp+-aq)cof.vi+cftpp+iq+7pqr)c o fM>' i ) 



" nnc{pr-t-q){\-rcqf.oi){ 4(pp — qq) 



^Tom.XIlLNou.Comm. S fi qui- 



