Question

integral cos15xcos4x dx @loser66

Answer 1

just apply formula cos a cos b = 1/2( cos (a+b) + cos (a-b) ) , your a = 15x, your b = 4x . that's it

Answer 2

1/2(cos(19x)+cos(11x)) is that all?

Answer 3

yup, and then take integral term by term

Answer 4

damn, i expected it to be more difficult....well, thats one down

Answer 5

hehehe... be on the Earth!! please