# Simple harmonic motion and damping

1. Aug 12, 2012

### Lamarr

I have to solve the following D.E. which describes how the amplitude of oscillation r, changes with time.

$$r=f(t)$$

$$\frac{dr^{2}cos^{2}t}{dt}=rsint$$

How do I find r?

2. Aug 15, 2012

### lugita15

Start by applying the product rule.