# Need help evaluating a limit

1. Oct 13, 2015

### Loststudent22

1. The problem statement, all variables and given/known data
$\lim_{\alpha\to\omega}-\frac{\alpha r_0}{\omega(\omega^{2}-\alpha^{2})}\sin(\omega t)+\frac{r_0}{\omega^{2}-\alpha^{2}}\sin(\alpha t)$

2. Relevant equations
I feel I will need to use fact $\frac{d}{d\omega}\sin(\omega t)=t\cos(\omega t)$

3. The attempt at a solution
Nope not sure how to start this one I'm rusty on limitis as it is and basic idea of trying l hopitals rule or factoring tricks are not working.

Thanks for any help

2. Oct 13, 2015

### Ray Vickson

Show us what you did, so we can point out if you made some errors. (Hint: you must have made some.)

3. Oct 13, 2015

### Loststudent22

Yeah I need a hint how to even approach this limit because my calculus 1 techniques are not really going anywhere

4. Oct 13, 2015

### Ray Vickson

Show us the calculus 1 techniques you used, so we can see why you say they are not going anywhere.