Question: Given the points P = (1, 2, 3), Q = (3, 5, 7), and R = (2, 5, 3), find:
(a) A unit vector perpendicular to a plane containing P, Q, R.
(b) The angle between P Q and P R.
(c) The area of the triangle P QR.
(d) The distance from R to the line through P and Q.