J & K CET Engineering J and K - CET Engineering Solved Paper-2014

  • question_answer
    Let \[A\,\,(2,\,\,-3)\]and \[B\,\,(-2,\,\,1)\] be vertices of a triangle ABC. If the centroid of this triangle moves on the line 2x + 3y = 1, then the locus of the vertex C is the line

    A)  \[3x-2y=3\]    

    B)  \[2x+3y=9\]      

    C)  \[2x-3y=7\]     

    D)  \[3x-2y=5\]

    Correct Answer: B

    Solution :

    Let coordinate of third vertex be \[C({{x}_{1}},\,{{y}_{1}})\] Then, centroid of triangle \[=\left( \frac{2+(-2)+{{x}_{1}}}{3},\frac{-3+1+{{y}_{1}}}{3} \right)=\left( \frac{{{x}_{1}}}{3},\frac{{{y}_{1}}-2}{3} \right)\] Since, centroid of this triangle moves on the line \[2x+3y=1\] \[\therefore \] \[2\left( \frac{{{x}_{1}}}{3} \right)+3\left( \frac{{{y}_{1}}-2}{3} \right)=1\] \[\Rightarrow \] \[2{{x}_{1}}+3{{y}_{1}}-6=3\] \[\Rightarrow \] \[2{{x}_{1}}+3{{y}_{1}}=9\] Hence, the locus of the vertex C is the line \[2x+3y=9\]


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