4io DE PERTVRBATIONE M0TV5 



20. Ex his (Jiiiibus nequuio.iibus difTercntiali- 

 bus primi gradus cliJamus diSoreiitiiie d X.\ quoi 

 fit dum primi iii fi.i. t altcra vero in — cof / du- 

 citur , tum enim proJit 



yj-\-tfWdt''-^M.tfWdt.Cm.t-\-(in.tf\5d[Qo(.t _ 

 ■-2coi:t/Vdt.co[.t -co^.tfVdt. [111.1" ^ 



ficque hinc impetramus 

 v/- r^ j . + 2 C^i^-tf V dt. (\n.t -C\n.t fV d t.coC. t 

 X--2/ ^"^^j^.^oijf^j^t.cof.t+coC.t/Udt.Citt.t 



Qiio autcm hiiic facilius etiam alteram coordiiiatam 

 j cruamus , vtamur formuhi iam fupra inuenta 

 dY':=^-zX'dt-dtfWdt, hoc cft 

 dY'=:z+:idtf\dt-+dt.Cm.t/VdtCin.t+2dtCin.t/Vdt.coC.f 

 - 4. tf'/.cof t/W dt.coC.t — 2 dt.coC.tfVdt.Cxn.t 



quas fingulas partes fcquenti modo integramus 



fdtfWdf=.tfV dt-fVtdt 

 qOae rfedudio autem nihil iuuat: 

 /</;nn.//V^ffm.f:=-cor;/Vrt'^fin.r+/Vrt/.fin.rcof./ 

 fdt coC.t/V dt coC.t-i- CmjfV dt. coC. t-fVdt Cin.t.coC.t 

 fdt fin. tfVdt cof ? z-cof tfVdt <.oC.t-\ fVdt.coC r' 

 fdt cof tfUdt fin. t zz -\- fin. t/Vdt. fin. t -/U r//.fin.;' 

 vnde colligimus fcqucntcm valorcm : 

 Y'.:z+3fdi/\dt + ^coC.rfVdt.Cin.t-2CoCtfVdtcoC.t+-fVdt 

 — 4 fin. tf\dt. cof. /- z C\n. if Vdt. Cin.t. 



21. 



