The force F = 30i + 20j - 10k (N). (a) Determine the magnitude of the moment of F about A. (b) Suppose that you can change the direction of F while keeping its magnitude constant, and you want to choose a direction that maximizes the moment of F about A. What is the magnitude of the resulting maximum moment? (F is at (8,2,-4)m and A is at (4,3,3)m).