J & K CET Engineering J and K - CET Engineering Solved Paper-2003

  • question_answer
    If a, b, c are different real numbers and \[a\,\,\hat{i}+b\,\,\hat{j}+c\,\,\hat{k},\]\[b\,\,\hat{i}+c\,\,\hat{j}+a\,\,\hat{k}\] and \[c\,\,\hat{i}+a\,\,\hat{j}+b\,\,\hat{k}\]are position vectors of three non-collinear points, then

    A)  centroid of \[\Delta ABC\] is s\[\frac{a+b+c}{3}\,(\hat{i}+\hat{j}+\hat{k})\]

    B)  \[(\hat{i}+\hat{j}+\hat{k})\] is not really inclined to three vectors

    C)  triangle ABC is a scalene triangle

    D)  perpendicular from the origin to the plane of the triangle does not meet it at the centroid

    Correct Answer: A

    Solution :

    Given, position vectors of a triangle are \[a\hat{i}+b\hat{j}+c\hat{k},\,\,b\hat{i}+c\hat{j}+a\hat{k}\] and \[c\hat{i}+a\hat{j}+b\hat{k}\] Then, centroid of triangle is \[\frac{a+b+c}{3}\,(\hat{i}+\hat{j}+\hat{k})\]


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