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Math Help - what is necessary for m to be 60?

  1. #1
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    what is necessary for m to be 60?

    In the figure below, ABC is an equilateral triangle. In order to have m = 60 degrees, which condition is necessary? think it is n=60 or



    CDE is an equilateral triangle.
    CDE is an isosceles triangle.
    n = 60 degrees
    n = 90 degrees
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    Last edited by sanee66; June 21st 2007 at 08:01 PM. Reason: pictures were not working
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  2. #2
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    The picture is not working.
    As well in your other posts.
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    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by sanee66 View Post
    In the figure below, ABC is an equilateral triangle. In order to have m = 60 degrees, which condition is necessary? think it is n=60 or



    CDE is an equilateral triangle.
    CDE is an isosceles triangle.
    n = 60 degrees
    n = 90 degrees
    Here's the first problem

    Note that \angle ACB \mbox { , } \angle m \mbox { and } \angle n are supplementary (they add up to 180^{ \circ}), since they are angles on a straight line.

    Since \triangle ABC is equilateral, \angle ACB = 60^{ \circ}

    So we have 60 + m + n = 180

    \Rightarrow n = 180 - 60 - m

    We want m to be 60^{ \circ} so plug that in

    \Rightarrow n = 180 - 60 - 60 = 60

    So n must be 60^{ \circ}
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