VARIATORVM, 151 



17. S\p conftans eft et r:^, ac manente, \t fupra, 

 GO—f, fietR— ^^z-2^ , et aeqnatio gcneralis dy— 

 dj^^P-^^ mutatur in dy-'-^'^^^^_2T^^ ^^ ^^^^ ^^- 

 qii.atio conftrui poffit fiat fradio ^^±^z=:xx , iniie- 

 nietarque 2^^=z^r^-^-h?:=,£^--^ , pofita k- 

 ___- , aaeoque ^ — ift::;!!^ , et -^—^^^^k xx^i' 

 Ipfa vero aequat. different. Ifochronae abit in dyzizxdZr 



dy_xdz_oxxdx_2xxdx__ 2dx __ ^hdx • dy ^ 



>t;i -^ — ^ — xx-^-k xx-i-\ — xx^i xx-^k '^'-H"^ z 



fignat in figura 4. angulum elementarem BGb, ergo 

 ang BG^=^-=^ -|l^,. SintrfA--i^,etrfB = 

 _:^^;j , et fiet ang. BGb:=z2dA-2dBVk , adeoque angu- 



lus BGO=r2A-2 BV^/t^- A. Sunt vero A et B anguli 

 quorum communis tangens eft znx , fed diuerfos radios 

 habent, cum anguli A radius fit i , alterius vero B, 

 zziVk. Aflumta vero a denotat condantem aliquem 

 anguhim addendum vel fubducendum ntque reqiienti ar- 

 gumento eliciendum , fi BG(— ;3) euadit zz OG;/), eua- 

 nefcit angulus BGO, fed hoc calu .r fit infinita, et angu- 

 li A et B quorum communis tangens fadla eft infinita 

 (imt ambo redi , quare fi r fit notaanguli redi, praece- 

 dens aequatio ang. BGQ=i2A-2Byy&-f-A , iam abit in 

 {2-oVk)r, -\-A—o, et Azz(2Vk-2)r adeoque aequatio 

 ang. BGOzi:2A-2B^/^.-4-A , mutatur in ang. BGO=:2 ^^' ^^* 

 (r-By^-2(r-A) Qaae concinnam praebct confiru- 

 (ftionem, capiendo nempe in linea indefinita CE partcs 

 CA— I, CD—Vk, ccinexcitataperpendiculariexpun- 



ao 



