-441 ) 147 ( ^'^^' 



"vnde fupra et infra per cof 2 ^ multif licando prodibiE 



tang. £ vp — 1 2 , 



l a a cof. 2 l, -+-ff 



qnam ergo conftrui oportet, atque hinc deriuatur fequens 



Conflrudio. 



■$. 24.. Capiatur angulus AFE— 180" — 2^, jp- Tah. Ut 

 /a mtem recla FE=:— ?j tum iungatitr re6la lE, et *"'& ^* 

 <iw^o «;7g^//i A I E et F I E bifecentur reCiis I M ^? I N, 

 j««f fn/«; tf»/i'i? «AT.f prlndpaks nojiri trianguU, 



Demonflratio^ 



Vocemus angulum A F E — 2 >} , vt fit 



* ^ r;::: 1 80° — 2 7) , quo valore adhibito fit 



^ , —iaa fin, 27; ^ a a fin. 2 ■>! 



tang. 2 vjy — i -i— — — ± — , 



— laa cof. 2.y^-\-ff -^a a cof. ^7} — ff 



tum Tero poiiatur reda F E zr '-^ ~ f , vt fiat 



■ tang.2vl>rr:,j/-2,; * 

 quare fi ex E in A F ducatur normalis EP, erit 



E P rr ^ fin. 2 -v] et F P — f cof. 2 'v)-, •• 



Ergo cum fit F 1 —fi erit 1 P — f cof 2 "v^ — /, ficquc 

 manifefto crit 



tang. A 1 E = ^^^-j = tang. 2 vp ; 



confequenter quia angulus A I E =z 2 >4^ , eo bifedo erit 

 AIM — >4^, ficque haec reda IM crit alter axis princi- 

 palis •, alter vero I N, qui ad hunc eft normalis, reperitur 

 bilecando angulum FIE. Q. E. D. 



T 2 Corol. 



i 



