[ 28 o ] 
rr= - • ^ — j, atque cof. B — cofs A A — , 
et fin. B = fin. aA — 1 — V — j. Q^E. I. 
Coroll, I. 
Hinc habetur cofi A x cofi B — X ~~~~ 
/X + * _l 4*«X, f * ?K * I. jy ?A 1 « 
— — -j ; fed, queinadmodum per 
I K _L «,>■ A + 1 _1_ rn x + 1 
hoc lemma eft — cof. A A, erit >•=: 
2 2 
/*•“ 1 -|- m K ~ 1 
cof A -f- i x A — cof. A -f- B, atque = 
cof. A — i x A — cof. B — A, adeoque cof. A x cof. B 
= 4 - cof. A -f- B 4 - i. cof. B — A. 
Atque hoc calculi methodo facile eruuntur fe- 
quentes formulae pro duobus angulis A et B, adver- 
tendo efte cof. B — A — cof. A — B, fin. B — A 
— fin. A — B, et cof. o — r. 
i°. Cof. A x cof. B — L. cof. A ~\- B -\- A cof. A — B. 
2°. Sin. A x fin. B — — 4 cof. A -f B 4. cof. A — B. 
3 0 . Sin. A x cof. B — 4. fin. A -j- B -|- 4. fin. A — B. 
Atque ex illis hae fequentes eliciuntur, 
4 0 . Cof. A B = cof. A x cof. B — fin. A x fin. B. 
5 0 . Cof. A — B = fin. A x fin. B cof. A x cof. B. 
6°. Sin. A B — fin. A x cof. B -\- cof. A x fin. B. 
7°. Sin. A — B — fin. A x cof. B — cof. A x fin. B. 
Turn ex his valores tangentium haud acgre deri- 
vantur. 
Quippc 
