How to find 3d vector if I know the other vector and the angle between them

Hi there; I am working in 3d space.I have three position vectors and I used the formula below to find the angle value between them.(fl,al and kl positions)

dv1 value is constant

ang = atan2(norm(cross(dv1,dv2)),dot(dv1,dv2));

Now I have different angle value and dv1 is constant How could I find the dv2 vector position?

Answer 1

[Mischa Kim]

In general, not at all. Since your vector dv2 could lie anywhere on a cone that is defined by dv1 (as the symmetry axis) and the given angle. If, at least, you know the plane dv2 needs to lie in you have only two more choices.