Find the general value of `theta` from the equation `tantheta+tan3theta=2tan2theta`.

Explanation

To solve the equation \( \tan \theta + \tan 3\theta = 2 \tan 2\theta \), we can follow these steps:

### Step 1: Rewrite the equation using trigonometric identities
We know that:
\[ \tan A = \frac{\sin A}{\cos A} \]
Using this, we can rewrite the equation:
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