50 DE SFPERFICIEBFS 



pi:Uur^CH(-*-^i^-) = 5-^c^-:r/. et CK-^)- 

 "2?^^6j3p7' ^^ P^^ ^"^'' rcdas DH, DI fuas rcfpe- 

 (ftiuas curuas t-angentes pkinum transirc intclligacnr , pla^ 

 num iftud luperlicicm in puuclo dato D coatinget. 



Aqiiatio F. az- '\-bjz-\-cj'-—exz-]rfx--\~gz-bx—o. 



XIII. Haec aequatio cft ruperficiei conoJdis Elli- 

 ptici vel llibindc etiam Coni Elliptici. Nam flida .c;~<?, 

 aequatio remancns cy'^-\-jx-—hx~o efl: aequatio bafis 

 Conoidis^ quam appa-ret clTc Elifpfm, cuius axis trani- 

 ucrfus ^j ■, et cius coniugatus ^j^j- 



Vertex Conoidis inuenitur vt in exemplo § prae- 

 cedcntis , aequatioiics vero A et B in pracfcnti exem- 

 pro fiint Pi.. .bz-\- icyzizo^ et ^ . .ez— 2fx-r- h~o., 

 et fuffccftis aeltimationibus liisce elicitis, proueniet (Z;/* 

 — ji^acf-\- cs- )z-^i_ ^cfs— 2 veh)z -ch- ., aequatio- 

 magmtadinem maximae applicatae z dcfaiiens. 



Tabuia VI. Porro circa direflriccm AZ. dcfcripta fit Ellipfis 



AFG,. in qua AGF, in qua AGrrj ^ Sit VPrr;i:~ 

 maximae applicatac Zy atque adco-V \ertex Conoidis, 

 demiflTunie normali EZ in dircdricem quantum opus 

 eli produdam, dicantur AZ~/, et VT. — m.. Sub- 

 ftitutis-r^Ue in aequationibus iiipra inucntis A ct B , pro 

 is, X et j', litteris /;, /, ct w, inucnicntur b~^"' , \bi 

 fignum priuatiunm denotat puncftum P fitum efle in 

 oppofita. prrte dircdricis intuitu pund:i F, et g~- ^^ ■" 

 tertia rero ;ictM'iatio ( hj - — \a cf-\- ce" ) z- zz. etc. prac- 



bet g zn j^r- Videa- 



