Solve: `tan4 theta = tan2theta`

Explanation

To solve the equation \( \tan(4\theta) = \tan(2\theta) \), we can follow these steps:

### Step 1: Understand the Equation
We have the equation \( \tan(4\theta) = \tan(2\theta) \). This implies that the angles \( 4\theta \) and \( 2\theta \) differ by an integer multiple of \( \pi \) (since the tangent function is periodic with a period of \( \pi \)).

### Step 2: Set Up the General Solution
From the property of the tangent function, we can write:
\[
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