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Homework Help: Help with Finding Angles of an Octagon

  1. May 27, 2014 #1
    Hi all

    I was wondering if someone could help with the following:-

    I have a regular octagon.

    Find angle CBA, ACB, BAC.

    Lines BA and AC are equal in length.

    I have done the following:-

    Found all the internal angles and all the external angles.

    I know that I have an isosceles triangle because BA & AC are equal so the base angles are equal.

    My guys felling is that I need to divide 135 by 2 to get 67.5, so my base angles ate 67.5, 67.5 and my third angle is 45.

    But I cannot explain why I dividing 153 by 2 gives the correct answer can anyone explain?

    Attached Files:

  2. jcsd
  3. May 27, 2014 #2


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    Homework Helper

    For me, the easiest way to do this is to start with angle ##\hat{A}##, you should be able to find it without knowing any other angles. Hint: extend AC and BC past A.
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