Question: Let A = (0, 0, 0) and B = (2, 0, 0).
(a) Find a point C in the xy-plane that is a distance 2 from both A and B.
(b) Find a point D in 3-space that is a distance 2 from each of A, B, and C.
(c) Describe the figure obtained by joining A, B, C, and D with straight lines.