Prove that: ` tan 20^@tan 30^@tan 40^@tan 80^@=1`

Explanation

To prove that \( \tan 20^\circ \tan 30^\circ \tan 40^\circ \tan 80^\circ = 1 \), we can follow these steps:

### Step 1: Rewrite the tangent function
We know that:
\[ \tan \theta = \frac{\sin \theta}{\cos \theta} \]
Thus, we can rewrite the left-hand side (LHS) as:
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