The VectorAngle(U, V) command computes the angle between Vectors U and V by using the formula $\arccos \left(\frac{U·V}{\mathrm{Norm}\left(U\right)\mathrm{Norm}\left(V\right)}\right)$.

with(Student[LinearAlgebra]):

V1 := <1,0,1>;

$\mathrm{V1}≔\left[\begin{array}{c}1\\ 0\\ 1\end{array}\right]$

V2 := <1,1,0>;

$\mathrm{V2}≔\left[\begin{array}{c}1\\ 1\\ 0\end{array}\right]$

VectorAngle(V1, V2);

$\frac{\mathrm{\pi }}{3}$