9th Class Mathematics Heron's Formula Question Bank Herons Formula

  • question_answer
    Tanya joined four triangles of cardboard to create a mask of Joker as shown in the given figure. Find the total area of the mask. (Given\[\sqrt{2}=1.41,\sqrt{3}=1.73\]]

    A) \[59.86\,c{{m}^{2}}\]             

    B)        \[50\,c{{m}^{2}}\]                  

    C)        \[59\,c{{m}^{2}}\]                  

    D)        \[53\,c{{m}^{2}}\]  

    Correct Answer: A

    Solution :

    Area of I & II part \[=2\times \frac{\sqrt{3}}{4}\times {{(2)}^{2}}=2\sqrt{3}\,c{{m}^{2}}=3.46\,c{{m}^{2}}\] Since, \[s=\frac{6+11+15}{2}=16\,cm\] [For III & IV part] \[\therefore \]Area of III & IV part \[=2\times \sqrt{16\times 10\times 15\times 1}\] \[=56.4\,c{{m}^{2}}\] Hence, total area of the mask \[=(3.46+56.4)\,c{{m}^{2}}=59.86\,c{{m}^{2}}\]


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