# Thread: some kind of fourier series

1. ## some kind of fourier series

How to find the coefficients An and Bn ? (see attached file)
Any help would be appreciated !

2. The issue here is that you have sinh and sin, so I am unsure how to solve. However, if you could get just sinh or cosh everywhere then you would multiply both sides by cosh or sinh, respectively. Then integrate over the domain.

3. Originally Posted by lvleph
The issue here is that you have sinh and sin, so I am unsure how to solve. However, if you could get just sinh or cosh everywhere then you would multiply both sides by cosh or sinh, respectively. Then integrate over the domain.
sinh and cosh do not generate an orthogonal basis over the given interval

CB

4. You're right they don't.