BCECE Engineering BCECE Engineering Solved Paper-2014

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

    A) 2x + 3y = 9          

    B)  2x - 3y = 7         

    C) 3x+2y=5                              

    D) 3x-2y=3

    Correct Answer: A

    Solution :

    Let (x, y) be the coordinates of vertex C and \[({{x}_{1}},{{y}_{1}})\] be the coordinates of centroid of the triangle. \[\therefore \]  \[{{x}_{1}}=\frac{x+2-2}{3}\] and \[{{y}_{1}}=\frac{y-3+1}{3}\] \[\Rightarrow \]               \[{{x}_{1}}=\frac{x}{3}\] and \[{{y}_{1}}=\frac{y-2}{3}\] Since, the centroid lies on the line 2x + 3y = 1. \[\therefore \]  \[2{{x}_{1}}+3{{y}_{1}}=1\] \[\Rightarrow \]               \[\frac{2x}{3}+3\frac{(y-2)}{3}=1\] \[\Rightarrow \]               \[2x+3y-6=3\] \[\Rightarrow \]               \[2x+3y=9\]which is the required locus of vertex C.


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