1. ## Integration

$\int\frac{1}{3 + 2cos(x)}*dx$ let cos(x) = ?

2. Originally Posted by Selim
$\int\frac{1}{3 + 2cos(x)}*dx$ let cos(x) = ?

integrate 1&#x2f;&#x28;3&#x2b;2cosx&#x29; - Wolfram|Alpha

Click on "show steps"

3. How did they know to do that?

4. Originally Posted by Selim
How did they know to do that?
It is a standard substitution known as the Weierstrass substitution. There are logical mathematical reasons for where it comes from but which are beyond the scope of what you're learning.