Prove that `(4cos^2 9^0-3)(4cos^2 27^0-3)=tan9^0dot`

Explanation

To prove that \((4\cos^2 9^\circ - 3)(4\cos^2 27^\circ - 3) = \tan 9^\circ\), we can use the trigonometric identity for \(\cos 3\theta\).

### Step 1: Use the identity for \(\cos 3\theta\)

The identity for \(\cos 3\theta\) is given by:
\[ \cos 3\theta = 4\cos^3 \theta - 3\cos \theta \]
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