Evaluate: `inttan^4x dx`

Explanation

To evaluate the integral \( \int \tan^4 x \, dx \), we can follow these steps:

### Step 1: Rewrite the Integral
We can rewrite \( \tan^4 x \) as \( \tan^2 x \cdot \tan^2 x \):
\[ \int \tan^4 x \, dx = \int \tan^2 x \cdot \tan^2 x \, dx \]

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