# Integration

• Mar 21st 2010, 08:29 PM
Selim
Integration
$\int\frac{1}{3 + 2cos(x)}*dx$ let cos(x) = ?
• Mar 21st 2010, 09:05 PM
harish21
Quote:

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"
• Mar 21st 2010, 10:03 PM
Selim
How did they know to do that? (Wait)
• Mar 22nd 2010, 02:55 AM
mr fantastic
Quote:

Originally Posted by Selim
How did they know to do that? (Wait)

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.