Q)
The angle between the planes \( \overrightarrow r .(3\hat i − 4\hat j +5\hat k) = 0 \: and\: \overrightarrow r .(2\hat i − \hat j − 2\hat k) \)is \[ \begin{array} (A)\: \frac{\pi}{3} \quad & (B) \: \frac{\pi}{2} \\ (C)\: \frac{\pi}{6} \quad & (D) \frac{\pi}{4} \end{array} \]
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