9th Class Mathematics Quadrilaterals Question Bank Quadrilateral

  • question_answer
    If ABCD is a quadrilateral whose diagondals AC and BD intersect at O, then:

    A)  \[\left( AB+BC+CD+DA \right)<\left( AC+BD \right)\]

    B)  \[\left( AB+BC+CD+DA \right)>2\left( AC+BD \right)\]

    C)  \[\left( AB+BC+CD+DA \right)>\left( AC+BD \right)\]

    D)  \[AB+BC+CD+DA=2\left( AC+BD \right)\]

    Correct Answer: C

    Solution :

    (c):  In \[\Delta ABC,\Delta ACD,\Delta BCD\] and \[\Delta ABD\] \[AB+BC>AC\] \[CD+DA>AC\] \[BC+CD>BD\] \[DA+AB>BD\] Adding above inequalities \[2\left( AB+BC+CD+DA \right)>2\left( AC+BD \right)\] \[\Rightarrow \]\[AB+BC+CD+DA>\left( AC+BD \right)\]


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