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Sit mine Bj3 elementum curvae datae, A / B / positio 

 perpendicuïi AB respectu hujus curvae, quippe ita motae 

 ut punctum B descripserit elementum BB aequale elemen- 

 to Yv; exhibeant porro curvae Y fi et 1B arcus curvaium 

 curvae A similium descriptarumque punctis fi et B, atque 

 designet B / fi elementum prions curvae, quo absoluto punc- 

 tum fi cadit in B'. 



His stabilitis determinanda est lineola B / B. Hune 

 in finem ponantur TV — q, DV =z p, TR = î), VR zh w, 

 BZ — u, DZ — t, ÇZ' — u, DZ' — t', arc. DT=z(p, BD=\\* 

 et (3D — vj/. 



Rectis autem fia et BA exhibitis simili modo ut in 

 jproblemate praecedente applicata YX, erit : 



g^ _. <! (.* — f>) — w(a — g) 



et pa - ^-rt-^-V ( PrabL L > 



hineque : 



fia — BAz=:fiy — *J£=£ =*>&-«•) _ gèt-ndu f 



unde fit : 



yB=z VBfi*-fiy*~ /dv{,*_Ç2lE^ u J! — ^±^2!, 



Ope solutionis probl. praec. autem invenitur : 



I' et = — [<I> — n|/ + '^'- ^^''."^j et 

 V A' — — py — ^ + ^ u '-^± w ' (f/ --^], 



Mémoires de i >Ac<i4. T. VI. 1 9 



