42 
MEMORIAS CIENTIFICAS I L1TERARIAS 
a 2 cos x + b 2 cos x — a 2 cos x— absen x 
(a cos x + b sen x) (a 2 + b 2 ) 
+ a 2 + b‘- 
d a cos x + d b sen x 
a 2 + b 2 J a cos x.+ b sen x 
f a 2 r b 2 X 
a x 
-TT- L (a cos x -f b sen x) + — -— ■■■ , 
-f-b 2 v 7 a + b 
22. f sen p x cos q x d x 
S sen (p + q) x d x + “ f sen (p— q) x d x 
cos(p + q)x cos(p + q)x 
p + q 
p— q 
22. f cospxcosqxdx = — 
sen (p + q)x_ sen (p— q) x 
p-4-q 
p q 
23. /cos (ax + b) cos (a 1 x~tb 1 ) d x 
sen [ (a + a 1 ) x + b + b 1 ] 
a (a + a 1 ) 
+ 
sen [ (a— a, 1 ) x + b — b 1 ) ] 
2 fa — a 1 ) 
(Tannery, 511) 
24. / sen (a x + b) sen (a+x + b 1 ) d x 
