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In several posts post1 and post2 have been shared how to obtain a dihedral angle with four points or their two planes. But ... How can one know if that dihedral angle is positive or negative?

  • What I have in mind to clasify them is the following diagram:

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Mort
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Another.Chemist
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    I'm voting to close this question as off-topic because it's a Math question. Nothing directly related to computer programming. – everton Oct 28 '17 at 03:18
  • I'm voting to close this question as off-topic because it is about geometry and [math.se] instead of programming or software development. – Pang Oct 31 '17 at 01:22

1 Answers1

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Calculate triple product of vectors P1P2, P2P3 and P3P4.

Sign of the value of this triple product shows handedness of vector triplet (right-handed or left-handed) and corresponds to the sign of dihedral angle

MBo
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