Working in 3d space, I'm given the vector $A=(1,2,3)$ and I'm supposed to find the smallest angle $\theta$ between $A$ and the x-axis.
Does it have to do with setting the x-axis as a vector, i.e: $R$ and calculating $cos\theta=(A*R)/(|A||R|)$ ?
I'm not really sure where to even begin.
edit: This is my guess: $A=(1,2,3)$ and x-axis$=R=(1,0,0)$ so that $|A|=\sqrt{(1^2+2^2+3^2)}=\sqrt{14}$
and $A*R=1*1+2*0+3*0=1$
so that $cos\theta=1/\sqrt{14}$ giving an angle of $\theta=74.5^o$
Is this correct?