Find the principal value of `cos^(-1)(1/sqrt2)`.

Explanation

To find the principal value of \( \cos^{-1}\left(\frac{1}{\sqrt{2}}\right) \), we can follow these steps:

### Step 1: Set up the equation
Let \( y = \cos^{-1}\left(\frac{1}{\sqrt{2}}\right) \). By the definition of the inverse cosine function, we have:
\[ \cos y = \frac{1}{\sqrt{2}} \]

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