CARTESIl CONCINKECONSTRVENDIS. zi 



AN-f^.^ vcrfus Q_, duAaquc NG parallcb L/, ^^s- 3. 

 qu.x BB prodU(ftx occurrat iu G, crit hoc pundum 

 vcrccx parabols. Ejus paranicrcr vcro, qu:im tt 

 dcinceps vocabmnis erit ——^^^ — . Pono autcm a, 

 (3 et '5 xquationis A cfle fmgulas affirmativas. His 

 pofitis, vcrticcG, parametro Trn:^^^^^— defcripta 

 circa diametrum GK parabola TG/^ pars ejus qux 

 c(l in angulo LAQ^dat omnes -\-j , et pars ejus qux 

 cll in angulo /AQ^dat omnes —j. 



DuLta enim rcda FK/ parallcla L/, vocandoque 

 AE^.v , KF=r, erunt BK— ^, et BG^-iiT^^-^» 

 ergo GK-(.vV/p'^)^7^. Quare V^tt GK=:1/ 

 ^•^-t-"3&)'l^'^^^/#^=^^(^l^-v-|-«,f)=2, ncc 



nonEK=.'^, quarcj-=|^4±V^(=-B^^vV-^). 

 Qiii erat locus conftruendus. 



Sccundo , fi ambx quantitates ip^S^-ajts , ec 

 $S-a<^ fint affirmativx, erit .v=^^ negativa, 

 adeoque in hoc cafu AN=i§^3 capicnda efl ad 

 partes ipfius P, dudique NG parallela LL, crit nunc 

 vertcx G parabolx ad partes P inter A & P, para- 



mctcr iT=r^^^— , ut in cafu prxcedenti, et para- 

 bohi qualis Fig. 3. 



T^r//{>, fi^-J-aCpfit adhuc pofitiva, fed ^^^-las 

 negativa , invcnietur x—^~^ affirmativa. Pro- Fig, .^. 

 pterea capienda clt verfus Q, pars AN=^;^';^ 

 proptcrca paraboU FG/, verticc G , parametro 



C 3 711= 



•'i,'- 3. 



