Constructions of the inversion of a point P in a circle

In each of these figures, it is alleged that the point Q is the inversion of point P in the red circle (and vice versa).  Give reasoning that shows this is true and also answer the following questions.

Questions

  1. In each case, give reasoning to explain why Q is the inversion of P, based on the definition of inversion.
  2. In each case, explain how one can start with the circle and P exterior to the circle and construct Q.
  3. In each case, explain how one can start with the circle and Q interior to the circle and construct P.
  4. For which of the constructions does the construction of Q work even when P is interior to the circle as well as exterior (so it would work as a single Sketchpad construction of the inversion of P)?
  5. Which is your favorite or your candidate for simplest and easiest construction of the inversion of P for the two cases: P exterior and P interior?