If `tan theta+tan(60^(@)+theta)+tan(120^(@)+theta)=3,` Prove that:
`(3tantheta-tan^(3)theta)/(1-3tan^(2)theta)=1`

Explanation

To solve the problem, we start with the given equation:

**Given:**
\[ \tan \theta + \tan(60^\circ + \theta) + \tan(120^\circ + \theta) = 3 \]

### Step 1: Rewrite the equation using properties of tangent
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