10. Consider the planes P of equation $4x + 9(y - 3) - 7z = 5$, and Q of equation $9x - y = 5$.
(a) Find the angle between the two planes. If you don't have a calculator, you can leave it as
you would enter it in a calculator.
(b) Give the point in Q that is closest to (1, 1, 1).
(c) What is the distance between (1, 1, 1) and the plane Q?