# HNC Math trig question

I am stuck on this question on my course, the workbook dosnt explain the concept very well. help would be appreciated.

You are measuring the force F, acting on an electrical conductor, which is subject to a strong magnetic field. The current may be modelled in three-dimensional space as:
𝐼=−7𝑖−6𝑗+9𝑘
and the magnetic field as: 𝐵=5𝑖−3𝑗+4𝑘
Determine the force F, as the cross product of the current vector and magnetic field vector, (i.e., find 𝐼×𝐵). Using a 3-dimensional Cartesian axis system, draw all three vectors, or use software to do so.
c) Using the dot product, determine the angle between the current vector and the magnetic field vector.
Well, you are given B and I but the total force would also require you to know what length of conductor you have.

However, putting that to one side, the cross product gives you a vector that is at right angles to both of the input vectors and hence gives you the direction of the force (provided you do the cross the correct way round).

Either we are missing some of the question or you just need to normalise somewhere and give the force per metre of conductor.