Saturday, July 4, 2009

Arithmetic Mean, Geometric Mean, Harmonic Mean, Root Mean Square

Proposed Problem
Click the figure below to see the geometric illustration of Arithmetic Mean, Geometric Mean, Harmonic Mean, Root Mean Square.

 Arithmetic Mean, Geometric Mean, Harmonic Mean, Root Mean Square.
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Arithmetic Mean, Geometric Mean, Harmonic Mean, Root Mean Square
Level: High School, SAT Prep, College geometry

1 comment:

  1. 1. a+b=OC+CB=AB=2.OD
    So OD=(a+b)/2= AM(a,b)
    2. AEB is a right triangle. Relation in right triangle give CE^2=CA.CB= a.b
    So CE= SQRT(a.b)=GM(a,b)
    3. Relation in right triangle OCE give
    EC^2=EF.EO => EF= EC^2/EO
    EC^2=a.b , EO=DO=(a+b)/2
    So EF=2a.b/(a+b)= HM(a,b)
    4. In right triangle OCD we have CD^2=OD^2+OC^2
    But OD=(a+b)/2 , OC=(a-b)/2
    So CD^2=2(a^2+b^2) => CD=RMS(a,b)
    5. In right triangles ODC and CEF we always have DC >OD and CE > EF
    In circle O we always have OD > CE
    So RMS (a,b) > AM (a,b) > GM (a,b) > HM (a,b)
    6. AM(a,b).HM(a,b)=(a+b)/2 x (2.a.b)/(a+b)= ab= GM(a,b)

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