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Homework Help: Scalene triangle angles

  1. Aug 11, 2016 #1
    1. The problem statement, all variables and given/known data
    The three angles of a scalene triangle are x degrees, (x-12) degrees and (2x+6) degrees. What sizes are the angles?

    bandicam 2016-08-11 20-13-13-110.jpg

    2. Relevant equations
    Triangle = a+b+c =180
    Scalene = no equal size or angles

    3. The attempt at a solution
    So what do you do with (x-12) degrees and (2x+6) degrees?
    I tried putting them all in an equation to isolate x but it was an incorrect approach. I can't equally divide the triangle since it's a scalene triangle. Can someone give me a clue?
    Last edited: Aug 11, 2016
  2. jcsd
  3. Aug 11, 2016 #2


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    Good. write it out using a+(b+c) = a+ b+ c etcetera...
  4. Aug 11, 2016 #3


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    Your approach is right:

    a + b + c = 180
    => (x-12)+(2x+6) + x = 180

    Now isolate x, and verify your results by filling x in the original question.

    What exactly do you mean by this?
  5. Aug 11, 2016 #4


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    Hi Frank, :welcome: (a bit belated, but welcome nevertheless :smile:)
    I notice you had a similar problem earlier and managed to solve it. Do you recognize that you are in the same situation with the current problem ?
  6. Aug 11, 2016 #5
    Yeah but I'm not trying to find one variable, I'm trying to find 3 angles, according to the answers
    bandicam 2016-08-11 20-08-46-363.jpg
    Obviously I know the answers now but I want to understand the step by step process behind it so I can learn from it.
  7. Aug 11, 2016 #6
    Thanks a lot man, I got confused but now I understand it, after isolating x I just plug it into the equation.

    x: 93/2 = 46.5 degrees
    (x-12): 46.5-12= 34.5 degrees
    180-81=99 degrees
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