Evaluate: `intcos2x" ln "(1+tanx)dx`

Explanation

To evaluate the integral \( \int \cos(2x) \ln(1 + \tan x) \, dx \), we can use integration by parts. Let's denote:

- \( u = \ln(1 + \tan x) \)
- \( dv = \cos(2x) \, dx \)

Now, we need to find \( du \) and \( v \).

### Step 1: Differentiate \( u \) and Integrate \( dv \)
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