JEE Main & Advanced Mathematics Complex Numbers and Quadratic Equations Question Bank Geometry of complex numbers

  • question_answer
    If \[{{z}_{1}},{{z}_{2}},{{z}_{3}}\] are affixes of the vertices \[A,B\] and \[C\] respectively of a triangle \[ABC\] having centroid at \[G\] such that \[z=0\] is the mid point of \[AG,\] then

    A) \[{{z}_{1}}+{{z}_{2}}+{{z}_{3}}=0\]

    B) \[{{z}_{1}}+4{{z}_{2}}+{{z}_{3}}=0\]

    C) \[{{z}_{1}}+{{z}_{2}}+4{{z}_{3}}=0\]

    D) \[{{z}_{1}}+{{z}_{2}}+{{z}_{3}}=0\]

    Correct Answer: D

    Solution :

    The affix of G is\[\frac{{{z}_{1}}+{{z}_{2}}+{{z}_{3}}}{3}\]. Since \[z=0\]is the mid point of\[AG\]. Therefore affix of the mid-point of \[AG\] is 0. Þ \[\frac{\frac{{{z}_{1}}+{{z}_{2}}+{{z}_{3}}}{3}+{{z}_{1}}}{1+1}=0\Rightarrow 4{{z}_{1}}+{{z}_{2}}+{{z}_{3}}=0\]


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