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Thread: Find unknown angles of a triangle!!!

  1. #1
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    Find unknown angles of a triangle!!!

    Dear friends,

    I am unable to find out the unknown angles for the following triangle which I attached with this post.



    Angle BAD and angle BCD are the unknown angles need to be calculated. Given that lines AB=BC=CD and angle CDE = 108 degrees

    From my calculations: angle ADC = 180 - 108 = 72 degrees (angles on a straight line)

    angle BAD + angle BCD = 108 degrees (exterior angle of a triangle = sum of interior opposite angles)

    I could not proceed any further beyond this. I thought line DB (median) is bisecting angle ADC since line DB is bisecting line AC (AB=BC) but this only happens in case of isosceles and equilateral triangles.

    I am very much stuck here and seek your kind suggestions here. I am also suspecting something could be wrong in the diagram of the triangle or may be the unknown angles. Let me know where I am wrong. Thanks in advance.
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  2. #2
    Elite Member stapel's Avatar
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    Cool

    Quote Originally Posted by tantrik View Post


    Angle BAD and angle BCD are the unknown angles need to be calculated. Given that lines AB=BC=CD and angle CDE = 108 degrees
    Are we maybe supposed to assume that angle ACD measures ninety degrees?

  3. #3
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    Quote Originally Posted by stapel View Post
    Are we maybe supposed to assume that angle ACD measures ninety degrees?
    That is where I am also confused. The diagram provided by the math teacher did not state anything about angle ACD.

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    Quote Originally Posted by tantrik View Post

    The diagram provided by the math teacher did not state anything about angle ACD

    If the phrase "right triangle" does not appear in any of the materials for this exercise, then you might ask about angle ACD.

    In the meantime, you could follow Stapel's suggestion, and set angle ACD to 90 degrees (in order to proceed).

    I also note that those stroke marks appearing in segments AB, BC, and CD could denote that those three segments all have the same length. That info might come in handy.

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