Answer
36.87 degrees
Work Step by Step
To find the angle between two vectors, use the following:
$\cos θ = \frac{u * v}{|u||v|}$
Given u = <4, 0, 2> and v = <2, -1, 0>
$\cos θ = \frac{<4, 0, 2> * <2, -1, 0>}{|\sqrt {4^2 + 0^2 + 2^2}||\sqrt {2^2 + (-1)^2 + 0^2}|}$
$\cos θ = \frac{8 + 0 + 0}{|\sqrt {20}||\sqrt {5}|}$
$\cos θ = \frac{8}{10} = \frac{4}{5}$
θ = 36.87 degrees