Question

A vector has equal, positive x and y components and zero z component. What is the angle between this vector and the x axis?

Answer 1

As far as x and y components are equal, the vectros is a diagonal of the square drawn on the picture. As far as a diagonal of a square bisects its angle $90\degree$, the angle between this vector and the x axis is $45\degree$.

Answer. $45\degree$.