10th Class Mathematics Coordinate Geometry Question Bank MCQs - Coordinate Geometry

  • question_answer
    If the point \[P(k-1,2)\] is equidistant from the points \[P(k-1,2)\] and \[B(k,5),\] the value of k is/are:

    A) \[2,3\]

    B) \[-2,4\]

    C) \[1,5\]

    D) \[5,-1\]

    Correct Answer: C

    Solution :

    [c]\[AP=BP\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,A{{P}^{2}}=B{{P}^{2}}\](By distance formula)
    \[\therefore \,\,{{(k-1-3)}^{2}}+{{(2-k)}^{2}}={{(k-1-k)}^{2}}+{{(2-5)}^{2}}\]
    \[\Rightarrow \,\,{{(k-4)}^{2}}+{{(2-k)}^{2}}={{(-1)}^{2}}+{{(-3)}^{2}}\]
    \[\Rightarrow \,\,{{k}^{2}}+16-8k+4+{{k}^{2}}-4k=1+9\]
    \[\Rightarrow \,\,2{{k}^{2}}-12k+10=0\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,{{k}^{2}}-6k+5=0\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,{{k}^{2}}-5k-k+5=0\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,(k-5)\,\,(k-1)=0\]
    \[\Rightarrow \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,k=1,5\]


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