Prove that:`tan6^0tan42^0tan66^0tan78^0=1.`

Explanation

To prove that \( \tan 6^\circ \tan 42^\circ \tan 66^\circ \tan 78^\circ = 1 \), we can use the properties of trigonometric functions. Here’s a step-by-step solution:

### Step 1: Use the complementary angle identity
We know that:
\[ \tan(90^\circ - x) = \cot x \]
Using this identity, we can rewrite some of the angles:
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