Solving Laplace Transform: 2\int_{0}^{t}f'(u)sin(9(t-u)du +5cos(9t)

[ensten]

Homework Statement

Find f(t) for:

$2\int_{0}^{t}f'(u)sin(9(t-u)du +5cos(9t), t\geq0$

The Attempt at a Solution

$F(s)=2\frac{9(sF(s)-f(0))}{s^2+81}+\frac{5s}{s^2+81}$

At this point i don't know what to do with f(0) since there are no initial conditions.
What do I do with it?

 

[vela]

It's just a constant that'll appear in your final answer. You'll have a term proportional to f(0).