3. Given that b = -31 + (4 + m)j - k ,c= -91+ 12j - (3 + m)k , , Q = (5 + m, 4,0 + m) and P = (-1,4 + m, -3). Find: a. The unit vector along the direction of a vector has Q as initial point and P as a terminal point (8 marks) b. Find the angle between the vectors b and & using scaler product (8 marks)