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 will follow these steps:

### Step 1: Rewrite the equation using trigonometric identities
We start with the equation:
\[ \tan \theta + \tan 3\theta = 2 \tan 2\theta \]
Using the identity \( \tan 3\theta = \frac{\sin 3\theta}{\cos 3\theta} \) and \( \tan 2\theta = \frac{\sin 2\theta}{\cos 2\theta} \), we can rewrite the equation as:
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