Sunday, June 8, 2008

Elearn Geometry Problem 116



See complete Problem 116
Area of Triangles, Excircles, Tangent. Level: High School, SAT Prep, College geometry

Post your solutions or ideas in the comments.

2 comments:

  1. S1+S2+[BGFH]=[PBE]
    S3+S4+[BGFH]=[DBQ]
    [PBE]=0.5BP.BE.sin(PBE)
    [DBQ]=0.5DB.BQ.sin(DBQ)
    line PBQ is the exterior bisector of ang(ABC)
    ang(PBE)=(180-B)/2+ang(DBE)=ang(DBQ)
    The right triangles PBD and BQE are similar
    BP.BE=DB.BQ
    hence [PBE]=[DBQ] and S1+S2=S3+S4
    .-.

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  2. BE = (s-c)
    [BPE]=1/2.rc.(s-c)=1/2.([ABC]/(s-c).(s-c)
    =1/2.([ABC]

    BD = (s-a)
    [BDQ]=1/2.ra.(s-a)=1/2.([ABC]/(s-a).(s-a)
    =1/2.([ABC]

    So [BPE] =[BDQ]
    [BPE]-[BGFH]=[BDQ]-[BGFH]
    S1+S2 = S3+S4

    widarto teddy
    wteddyad@yahoo.com

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