Monday, May 19, 2008

Elearn Geometry Problem 43



See complete Problem 43
Angles, Triangle. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

4 comments:

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  2. The solution is uploaded to the following link:

    https://docs.google.com/open?id=0B6XXCq92fLJJdTVoS3RUbVp4dVE

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  3. Reference my proof for Problem 42

    Let BD meet AC at G.

    Since Tr. ABC is isoceles and < ABC = 120-2@, < BCA = 30 +@

    In Tr. BCG, < GBC = 90-@ and < GCB = 30+@. So x must be 60

    Sumith Peiris
    Moratuwa
    Sri Lanka

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  4. [For the sake of easy typing, I will use "a" instead of alpha]
    <CBD=<CDB=90-a
    <CDE=90+a
    <DCE=90-x-a
    <BCE=90-x+a=<BAC
    <ABC=180-(90-x+a)-(90-x+a)=2x-2a
    With the help of problem 42, 2x-2a=120-2a
    2x=120
    x=60

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