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Cosine rule problems

  1. Nov 4, 2011 #1
    Hey,

    If I wanted to make up problems that are solved using the law of cosines, shouldn't it work out even if I arbitrarily choose side a, b, and θ? After all, any two sides and an angle between them form a triangle. Correct?
     
  2. jcsd
  3. Nov 4, 2011 #2
    Yes correct. I'm curious to know why you think choosing sides a b and theta wouldn't give you an answer for c.
     
  4. Nov 4, 2011 #3

    mathman

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    Science Advisor

    You're OK as long as the angle is < 180 deg.
     
  5. Nov 4, 2011 #4
    Even then you'd just have a triangle in the other direction. You would just have to change a sign(no pun intended).
     
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