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Good question

  1. Apr 13, 2004 #1
    Here's an interesting question which is related to proofs, one of the hardest chapters of math:

    If a circle can be drawn to pass through the 4 vertices of a Quadrilateral, we call this a "cyclic quadrilateral". What special properties do you think a cyclic quadrilateral has that wouldn't be true for any other quadrilateral?
  2. jcsd
  3. Apr 14, 2004 #2
    Just a quick guess: Right or acute angles?

  4. Apr 14, 2004 #3


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    A cyclic quadrilateral satisfies Ptolemaios' theorem, which states, for vertices A,B,C,D:
    (AC and BD diagonals)

    I don't think non-cyclic quadrilaterals satisfy Pt. th.
  5. Apr 14, 2004 #4
    Sum of every opposite pair of angles is π?
  6. Apr 14, 2004 #5


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    This smells like a question from a take-home test...
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