rOLYGONOrvVM RECTILINEORVM. 115 



ex quo fiet 



I -cof Y*-coC Y^^rcof.C'- acof.Ccor. ycof. -y'» ^iue 



1 4- 2 cofXcor. Y cof. y' — cof. C'-fcoC y' +cof y'^« 

 Conflat aiitcm efie 



coCCr^^^icof.Y:=^-4^;:=^^ corY'=^^7^; 

 his igitur valoribus (ubftitutis, fequens prodibic ae- 

 quatio : 



~ 4 6= e^ ~ 4C'«- 



fiue 



quae aequntio licet fit biquadratica , tamen vt qua- 

 dratica tradari potcfl:, qnum in ea non nifi quadrata 

 linearum ^, ^, f etc. occurrant. Simplicitatis igitur 

 gratia loco quadratorum ex litteris a,b,cetc. ipias 

 has litteras fcribere li(.ebit , tum autem fada euolu- 

 tionc nuflra aequatio hai^.c adipifcetur formam fatis 

 concinnam : 



ac ( b-\- e + d-hf- a - c)-\- e f [a + b+c+d-e-f) 

 -hbd{a+c+e-{-f-b-d) = abe-\-ecd-\-afd+bcfi 



vbi ohfcruandum littcras a^b^c ctc. non indigitare 

 "ip(as lineas AB,BC,CD etc. fed earum quadrata. 

 Pro hac aequatione notarc conuenit , producla ifU 

 ,ac,efybd inuoUiere lincas difcretcis , haec vero abe^ 

 ecd, afd, bcf ^ inuoluunt lineas , quae ad trianguU 

 formanda ccrto modo concurrunt. Caeterum quo- 

 modo ex hac acquationc quadratica dcterminari de- 



P 2 beat 



