10th Class Mathematics Coordinate Geometry Question Bank MCQs - Coordinate Geometry

  • question_answer
    The points (3, 2), (-2, - 3) and (2, 3) form a triangle name the type of triangle formed.

    A) equilateral

    B) isosceles

    C) right angle

    D) None of these

    Correct Answer: C

    Solution :

    Let the points are \[A\left( 3,\,2 \right)\], \[B\left( -2,\,-3 \right)\]and C (2, 3).
    Then,   \[AB=\sqrt{{{\left( -2-3 \right)}^{2}}+{{\left( -3-2 \right)}^{2}}}\]
                [\[\because\]distance\[=\sqrt{{{\left( {{x}_{2}}-{{x}_{1}} \right)}^{2}}+{{\left( {{y}_{2}}-{{y}_{1}} \right)}^{2}}}]\]
    \[=\sqrt{{{\left( -5 \right)}^{2}}+{{\left( -5 \right)}^{2}}}=\sqrt{25+25}=\sqrt{50}\]
    \[=7.07\] units (approx)
    \[BC=\sqrt{{{\left( 2+2 \right)}^{2}}+{{\left( 3+3 \right)}^{2}}}=\sqrt{{{\left( 4 \right)}^{2}}+{{\left( 6 \right)}^{2}}}\]
    \[=\sqrt{16+36}=\sqrt{52}=7.21\]units (approx)
    and \[CA=\sqrt{{{\left( 3-2 \right)}^{2}}+{{\left( 2-3 \right)}^{2}}}\]
    \[=\sqrt{{{\left( 1 \right)}^{2}}+{{\left( -1 \right)}^{2}}}=\sqrt{1+1}\]
    \[=\sqrt{2}=1.41\] (approx)
    Also, \[{{\left( \sqrt{52} \right)}^{2}}={{\left( \sqrt{50} \right)}^{2}}+{{\left( \sqrt{2} \right)}^{2}}\]
    \[\Rightarrow \,\,B{{C}^{2}}=A{{B}^{2}}+C{{A}^{2}}\]
    So, by converse of Pythagoras theorem,
    \[\angle A=90{}^\circ\]
    Hence, \[\Delta BAC\]is a right angled triangle.
       


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