Hinc igicur colligitiir qirantitas pbft fignum radicate vt fequitur 



-{-[a a b b + la a t; c^- ib If c c i 

 quae, deletis terminis fe dcflruentibus, reducitur ad hanc: 



'^aabb-^-iaacc-^-^bbcc^la^ — lb^-^^c'. 

 Quare cum ctiam arca S fit quam minima , idcoque 

 fin. S :=::: S, habebimus aream quaefitam : 

 S=:lV{kaabb-\-laacc-\-lbbcc-la*-;b'-lc% 



fiue 



S — [V {i^ a a b h -\- s. a a c c -\- 2 b b c c - a* ^ h* — c*) II 



quae ell formula notiflima pro area trianguli plani. 

 Inueftigatio fectinda, 



pro cofmu S. 

 4.' 1 5. Cum fit cof. S rz: - cof ( A 4- B + C), eiik 

 cof S — cof. A fin. B fin. C 4- cof B fln. A fm C 

 -+. cof. C fin. A fin- B — cof A cof B cof C, 

 quac quatuor membra feorfim euoluta dabiint: 



I. cof.Afin.Bfin.Cr::,^^^-^; ' " 



II. cof. B fin. A fin. C :r. -:^/^&- ; 



III. cof Cfin. Afin.B^i,-^: 



■ a (3 ) 



Pro termino poftremo erit primo \ 



cof. A cof. B - fa-,n )(^-a7) ^zj^ccay^fjy^^ 



hincque 



cof Acof.Bcof C — «P ">'-*« PP-^o^^y-P '^'V'v^«(^'v^+«^' i^^- ^^ l^ft^-t^P^V 



Jm.a-jm.b^jin.C^ ' 



