JCECE Engineering JCECE Engineering Solved Paper-2002

  • question_answer
    The point moves such that the area of the triangle formed by it with the points \[(1,\,\,5)\] and \[(3,\,\,-7)\] is\[21\,\,sq\,\,unit\]The locus of the point is:

    A) \[6x+y-32=0\]   

    B) \[6x-y+32=0\]

    C)  \[x+6y-32=0\]  

    D)  \[6x+y+32=0\]

    Correct Answer: A

    Solution :

    Given coordinates of a triangle are \[A(1,\,\,5)\]  and\[B(3,\,\,-7)\]. Let the coordinate of third vertex of a triangle be\[({{x}_{1}},\,\,{{y}_{1}})\]. \[\therefore \]Area of \[\Delta ABC=21\](given) \[\Rightarrow \]\[\frac{1}{2}[1(-7-{{y}_{1}})+3({{y}_{1}}-5)+{{x}_{1}}(5+7)]=21\] \[\Rightarrow \]               \[2{{y}_{1}}+12{{x}_{1}}-22=42\] \[\Rightarrow \]               \[12{{x}_{1}}+2{{y}_{1}}-64=0\] \[\Rightarrow \]               \[6{{x}_{1}}+{{y}_{1}}-32=0\] \[\therefore \]Locus of a point is                 \[6x+y-32=0\]


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