Answer
$0.73$ rad
Work Step by Step
The formula to calculate the angle between two planes is:
$ \theta = \cos ^{-1} (\dfrac{p \cdot q}{|p||q|})$
Here, $p=\lt 0,4,3 \gt$ and $q=\lt 3,2,6 \gt$
$|p|=\sqrt{0^2+4^2+3^2}= 5$ and $|q|=\sqrt{3^2+2^2+6^2}= 7$
Thus, $ \theta = \cos ^{-1} (\dfrac{p \cdot q}{|p||q|})=\cos ^{-1} (\dfrac{26}{ 35})$
or, $ \theta = 0.73$
