# Differential Equation

1. May 25, 2016

### chwala

1. The problem statement, all variables and given/known data
Solve and obtain an expression for x in terms of θ given $(3+ cos 2θ) dx/dθ = x sin 2θ$

2. Relevant equations

3. The attempt at a solution
.....$dx/x = ((sin 2θ)/(3+ cos 2θ))dθ$ ,

let $u = (3+cos 2θ)⇒ du/dθ= -2 sin 2θ$
thus

$∫dx/x = -1/2∫du/u$...........
are my steps correct?i can solve from here

2. May 25, 2016

### Simon Bridge

You noticed that it was 1st order seperable, and proposed a u-substitution for the resulting RHS: well done.
I didn't check your arithmetic - you have to do that yourself - but the reasoning is sound so far.