9th Class Mathematics Areas of Parallelograms and Triangles Question Bank Area of Parallelogram & Triangle

  • question_answer
    ABCD is a parallelogram. E is a point BC such that BE : EC = m : n. If AE and BD intersect in F, then what is the ratio of the area of \[\Delta \mathbf{PEB}\] to the area of \[\Delta \mathbf{AFD}\]?

    A)  \[m\text{/}n\]                           

    B)  \[{{\left( m\text{/}n \right)}^{2}}\]

    C)  \[{{\left( n\text{/}m \right)}^{2}}\]                               

    D)  \[{{\left[ m/{{(n+m)}^{2}} \right]}^{2}}\]

    Correct Answer: D

    Solution :

    (d):- In \[\Delta AFD\] and \[\Delta FEB\] \[\angle AFD=\angle BFE\]       (Vertically opposite angles) And  \[\angle ADC=\angle ABC\] \[\therefore \] \[\Delta AFD\tilde{\ }\Delta BFE\] So, \[\frac{ar\left( \Delta FED \right)}{ar\left( \Delta AFD \right)}=\frac{E{{B}^{2}}}{A{{D}^{2}}}=\frac{{{m}^{2}}}{{{\left( mn \right)}^{2}}}\] \[=\frac{{{m}^{2}}}{{{\left( mn \right)}^{2}}}={{\left[ \frac{m}{m+n} \right]}^{2}}\]


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