Show that: `cos(2tan^(-1)(1/7))=sin(4tan^(-1)(1/3))`

Explanation

To show that \( \cos(2 \tan^{-1}(1/7)) = \sin(4 \tan^{-1}(1/3)) \), we will evaluate both sides step by step.

### Step 1: Evaluate the Left-Hand Side (LHS)
We start with the LHS:
\[ \cos(2 \tan^{-1}(1/7)) \]
Using the double angle formula for tangent, we have:
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