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

  • question_answer
    A square and an equilateral triangle have equal perimeters. If the diagonal of the square is \[12\sqrt{2}\,cm,\]what is the area of the triangle?

    A) \[24\sqrt{2}\,c{{m}^{2}}\]                   

    B) \[24\sqrt{3}\,c{{m}^{2}}\]       

    C) \[48\sqrt{3}\,c{{m}^{2}}\]       

    D)   \[64\sqrt{3}\,c{{m}^{2}}\]       

    Correct Answer: D

    Solution :

    Diagonal of a square is \[12\sqrt{2}\,cm\] \[\Rightarrow \]\[2\sqrt{a}=12\sqrt{2}cm\Rightarrow a=12\,cm\] \[\therefore \]Perimeter of the square = 4a \[=4\times 12=48\,cm\] Perimeter of an equilateral triangle is 3a \[\Rightarrow 48\,cm=3a\Rightarrow a=\frac{48}{3}cm=16cm\] \[\therefore \]Area of equilateral triangle. \[=\frac{\sqrt{3}}{4}{{a}^{2}}=64\sqrt{3}\,c{{m}^{2}}\]


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