My simple wrong program skips necessary mathematical checks, but it got AC.

1 20 5 5
Answer: Impossible.
(Wrong solution skipped the check of cos(∠DAC) bounds; a cosinus must be from -1 to 1)

5 7 4 7
Answer: Impossible.
(Wrong solution skipped the check of the order of satelites; the test case is from the task subscription, I've just changed the positions of A and B satelites).

Unfortunately both tests are incorrect. "Impossible" means only "ambiguous" in this problem.

Oh, ok. Sorry :)