Find `intcos6xsqrt(1+sin6x)dx`

Explanation

To solve the integral \( \int \cos(6x) \sqrt{1 + \sin(6x)} \, dx \), we will use the substitution method. Here’s a step-by-step solution:

### Step 1: Choose a substitution
Let:
\[ t = 1 + \sin(6x) \]

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