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Smallest interior angle

  1. Nov 6, 2009 #1
    1. The problem statement, all variables and given/known data
    Find the smallest interior angle of the triangle ABC whose vertices are given.
    A = (3,1,-2), B = (3,0,-1), C = (5,2,-1)



    2. Relevant equations

    I think the equation arccos( U dot V / (lengthU)(lengthV)

    3. The attempt at a solution

    What i did is tried the formula for all combinatations: AB, BC, AC to get all the angles, and which ever was the smallest I choose. Unfortunately I do not get the correct answer.
     
  2. jcsd
  3. Nov 6, 2009 #2

    Mark44

    Staff: Mentor

    Show us what you did. You only need to find the angles between two pairs of line segments. Once you know two of the angles, you can find the third pretty easily.
     
  4. Nov 6, 2009 #3

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    All most the same thing but instead of using the dot product you could use the "cosine law" to find the angles.
     
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