10th Class Mathematics Mensuration Question Bank Mensuration

  • question_answer
    If the perimeter of an equilateral triangle is equal to the circumference of a circle, then the ratio of their areas is

    A)  \[\pi :\sqrt{3}\]               

    B)         \[\pi :3\]

    C)  \[\pi :9\]            

    D)         \[\pi :3\sqrt{3}\]  

    Correct Answer: D

    Solution :

     If perimeter of an equilateral triangle is p, then each side is of length \[\frac{p}{3},\] and area \[=\frac{1}{2}{{\left( \frac{p}{3} \right)}^{2}}\frac{\sqrt{3}}{2}=\frac{{{p}^{2}}\sqrt{3}}{36}\] If perimeter of a circle is p, then its radius is \[\frac{p}{2\pi }\] and       area \[=\pi {{\left( \frac{p}{2\pi } \right)}^{2}}=\frac{{{p}^{2}}}{4\pi }\] \[\therefore \] Required ratio \[=\frac{{{p}^{2}}\sqrt{3}}{36}\,:\,\frac{{{p}^{2}}}{4\pi }=\pi :3\sqrt{3}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner