9th Class Mathematics Areas of Parallelograms and Triangles Question Bank Areas of Parallelograms and Triangles

  • question_answer
    In the given figure, if \[ar(\Delta ABC)=28\,\,c{{m}^{2}}\], then \[ar(AEDF)=\]

    A) \[21\text{ }c{{m}^{2}}\]              

    B)        \[~18\,c{{m}^{2}}\]               

    C)        \[~16\text{ }c{{m}^{2}}\]                  

    D)        \[~14\text{ }c{{m}^{2}}\]           

    Correct Answer: D

    Solution :

    Form the given figure D,E,F are mid-points sides BC, AC, AB. Then, \[ar(\Delta \Alpha \Beta C)=ar[\Delta \Alpha F\Epsilon +\Delta FED+\Delta EDC+FBD]\] Also, \[ar\,\Delta \Alpha FE=ar\Delta FED=ar\Delta EDC=ar\Delta FBD\] \[\Rightarrow \]\[ar(\Delta \Alpha F\Epsilon )=\frac{ar(\Delta \Alpha \Beta C)}{4}=\frac{28}{4}=7\,c{{m}^{2}}\] Now, Area of parallelogram AEDF \[=ar(\Delta \Alpha \Epsilon F+\Delta EFD)=(7+7)c{{m}^{2}}=14c{{m}^{2}}\]


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