JEE Main & Advanced Mathematics Three Dimensional Geometry Question Bank Self Evaluation Test - Introduction to Three Dimensional Geometry

  • question_answer
    Which of the following statement is true?

    A) The point A(0, -1), B(2, 1), C(0, 3) and D(-2, 1) are vertices of a rhombus.

    B) The points A(-4, -1), B(-2, -4), C(4, 0) and D(2, 3) are vertices of a square.

    C) The points A(-2, -1), B(1, 0), C(4, 3) and D(1, 2) are vertices of a parallelogram.

    D) None of these

    Correct Answer: C

    Solution :

    [c] Here \[(a)A(0,-1),\,B(2,1),\,C(0,3),\,D(-2,1)\]. For a rhombus all four sides are equal but the diagonal are not equal, we see \[AC=\sqrt{0+{{4}^{2}}}=4\],
    \[BD=\sqrt{{{4}^{2}}-0}=4\]
    Since diagonals are equals therefore it is a square, not rhombus
    [b] Here             \[AB=\sqrt{{{2}^{2}}+{{(-3)}^{2}}}=\sqrt{13},\,BC\]
    \[=\sqrt{{{6}^{2}}+{{4}^{2}}}=\sqrt{52}\]
    Since \[AB\ne BC\] therefore it is not square.
    [c] In this case mid point of AC is
    \[\left( \frac{4-2}{2},\frac{3-1}{2} \right)\] or \[(1,1)\]
    Also mid-point of diagonal \[BD\left( \frac{1+1}{2},\frac{0+2}{2} \right)\] or (1, 1)
    Hence the points are vertices of a parallelogram.


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