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    Question

    In ∆ABC , G is the centroid , AB = 6 cm, BC= 8 cm and

    AC = 10 cm , find GD, where D is the mid-point of BC?
    A 2√86/3 cm Correct Answer Incorrect Answer
    B 2√7/3 cm Correct Answer Incorrect Answer
    C 8√7/3 cm Correct Answer Incorrect Answer
    D 2√13/3 cm Correct Answer Incorrect Answer

    Solution

    If AD is the median, then we know, AB² + AC² = 2{AD² + (BC/2)²} or 62 +  102  = 2{AD 2 + (8/2) 2 } or 36 + 100 = 2{AD 2 + 16} or 136/2 =  AD 2  + 16 or 68 = AD 2  + 16 or  AD 2  = 68 – 16 = 52  or AD = √52 = 2√3 Now G divides median in 2:1 so GD = 1/3 of AD = 1/3 of 2√3 = 2√3/3cm

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