Answer
$24$
Work Step by Step
We know that the angle between two vectors is:
$\theta =\cos^{-1} [ \dfrac{u \cdot v}{||u|| \space ||v|| }]$
Therefore, $\cos (\dfrac{\pi}{3}) = \dfrac{u \cdot v}{(4)(12) }$
or, $u \cdot v= 48 \times (\dfrac{1}{2})$
or, $u \cdot v=24$
