1. ## Integration

How do i integrate cos4xcosx ?
i used cos4x=2cos(^2)2x - 1
i dont know how to proceed.

2. Originally Posted by kandyfloss
How do i integrate cos4xcosx ?
i used cos4x=2cos(^2)2x - 1
i dont know how to proceed.
Use the product to sum identitety

List of trigonometric identities - Wikipedia, the free encyclopedia

3. Can you please show?

4. Originally Posted by kandyfloss
Can you please show?
Please show your attempt at using the formulae given in post #2.

5. Yeah i got : 1/2 (integral) cos3x + cos5x using the formula [took the 1/2 out]