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# Integration Help Watch

1. How to integrate sin(6x)cos(9x)??
2. (Original post by mil88)
How to integrate sin(6x)cos(9x)??
Have you covered complex integration yet?
3. (Original post by Calzs34)
Have you covered integration by parts yet?
Yes I have but firstly, I believe that by parts will not solve it as when you differentiate the trig function, you end up with another.
4. (Original post by mil88)
How to integrate sin(6x)cos(9x)??
Try using one of these product to sum formulae
Attached Images

5. (Original post by kingaaran)
Try using one of these product to sum formulae
Ok thanks, btw are they on the formula sheet (how did you find out about them?)
6. (Original post by mil88)
Yes I have but firstly, I believe that by parts will not solve it as when you differentiate the trig function, you end up with another.
Sorry, you're right - parts wouldn't work as you'll end up with a cycle of trig functions I edited it, you're supposed to use the equations as above stated by KingAaran.
7. (Original post by mil88)
Ok thanks, btw are they on the formula sheet (how did you find out about them?)
They are on the formula sheet It is usually quite helpful in such cases, because you can split the integral into one involving sin(ax) and one involving cos(bx) which makes it relatively simplistic after!
8. Parts would work:
Solve for
9. (Original post by kingaaran)
They are on the formula sheet It is usually quite helpful in such cases, because you can split the integral into one involving sin(ax) and one involving cos(bx) which makes it relatively simplistic after!
Indeed.
10. (Original post by MathsAndChess)
Parts would work:
...
But very overkill!
11. (Original post by MathsAndChess)
Parts would work:
Ok thanks!
12. (Original post by Zacken)
But very overkill!
Indeeeeeed my man holding a trophy over his head
13. Overkill is the way to do it man..

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