`lim_(xrarr0)(cos 2x-1)/(cosx-1)`

Explanation

To solve the limit \( \lim_{x \to 0} \frac{\cos 2x - 1}{\cos x - 1} \), we can follow these steps:

### Step 1: Rewrite the limit
We start by rewriting the limit:
\[ L = \lim_{x \to 0} \frac{\cos 2x - 1}{\cos x - 1} \]

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