Uestion 3 the position vectors of three points a, b and c with respect to a fixed origin o are (2,-2, 1), (4, 2, 1) and (1, 1, 3) respectively (a) write down unit vectors in the direction of lines ca and cb and calculate the of angle acb, in degrees, to 1 decimal place. (b) the midpoint of ab is m. find a vector equation of straight line passing through c and m (c) show that ab and cm are perpendicular. (d) find the position vector of point n on the line cm such that angle