hello, i need someone to verify or correct my solution.

I have two vectors u=[2;1;-2] and v=[1;2;3] and i need to find the cosine of the angle between them

my solution would be $\displaystyle cos \phi = - \frac {2} {3 \sqrt 14}$

any idea how i could verify this any other way ? i got maple, but i have no clue about the syntax, i just use the interface