Application (10 marks) 10. Solve for a if u = (-12, 6, a) and v = (4, -2, 4) are: a) Perpendicular (2 marks) b) Parallel 11. A small plane is travelling at 175 km/h on a heading of N8 E and is subjected to a 40 km/h wind from N80 E. Determine the ground velocity of the plane. (4 marks) 12. A triangle is defined by the points A(0, 1, 2), B(1, 0, 2) and C(-1, 2, 0). Find angle A of this triangle. (4 marks)