272 Francisci Bertelli 



f H-00 /f/A('-2)\ \ 



} -00 \ da I t 



(48) { , , S • 



i +00 /(i A(')\ I 



Itaque si ponatur 



(49) — i f (/_2)A('-2)-f-«'»B(-2) - «'(-^^) j=P(2) ; 



et 



(50) -x|a'.B(.)*a'(^^^^)j=Q(0; 



factor quadrati /?' evadet 



(t) — - 1 cos(3/-4-2x)H-cos(7--t-2j:).+.2cos7' | 



h-2'^*^P(2)cos(j/-4-2x)h-22'^Q(<)cosj>. 



27. Cum primus terminus factoris producti p' q' (D) ob for- 

 mulas (1 5) numeri i 7 vcrtatur in 



(51) --^ .cos/sin2(/-Kx)=— 2^Jsin(3/i-2x)*sin(7-,.2a:)j ; 



alter autem(/), (num.20), loco i posito (i — 2) in 



-hOO 



(52) —is a'2B('-2)sin(//^2.r) ; 



^ —00 



factor erit 



■^« ^ ^ -t-oo 



(«) _ —^ sin(3/-*-2x)-4.sin(7-4-2x) -t-lS a'2B('-2)sin(/;'^2.r) . 



2rt'*( ' *^ 



28. Tandem ad factorem quadrati c/' descendamus. Cum sit 



sin2(7-Hj:)=— ^[cos2(7-*-x)— 1 } , 



primus illius factoris terminus (15), (num. 17), erit 



(53) -^ .cosfsm\f^x)=—-T^j |cos(37-t-2x)-^cos(7-4-2x)-2cosj| ; 



secundus vero (2)i (num. 14), 



