SSC Sample Paper SSC CHSL (10+2) Sample Test Paper-3

  • question_answer
    A copper wire is bent in the form of an equilateral triangle and has area\[121\sqrt{3}c{{m}^{2}}\]. If the same wire is bent into the form of a circle, the area\[\text{(in}\,\,\text{c}{{\text{m}}^{\text{2}}}\text{)}\]enclosed by the wire is\[\text{(Take}\,\,\pi \,\text{=}\frac{\text{22}}{\text{7}}\text{)}\]

    A) \[364.5\]                       

    B) \[693.5\]

    C) \[346.5\]             

    D)        \[639.5\]

    Correct Answer: C

    Solution :

     Area of the equilateral triangle\[=\frac{\sqrt{3}}{4}\text{sid}{{\text{e}}^{2}}\] \[\Rightarrow \]\[121\sqrt{3}=\frac{\sqrt{3}}{4}\times \text{sid}{{\text{e}}^{2}}\] \[\therefore \]\[\text{Sid}{{\text{e}}^{\text{2}}}=\frac{121\sqrt{3}\times 4}{\sqrt{3}}=121\times 4\] \[\therefore \]Side\[=\sqrt{121\times 4}\]           \[=11\times 2=22\,\,\text{cm}\] \[\therefore \]Total length of wire\[=3\times 22=66\,\,\text{cm}\] If the radius of the circle be \[r\]cm, then \[2\pi r=66\] \[\Rightarrow \]   \[\frac{2\times 22}{7}\times r=66\] \[\Rightarrow \]   \[r=\frac{66\times 7}{2\times 22}=\frac{21}{2}\text{cm}\] \[\therefore \]Area of the circle\[=\pi {{r}^{2}}\]             \[=\frac{22}{7}\times \frac{21}{2}\times \frac{21}{2}=346.5\,\,\text{c}{{\text{m}}^{\text{2}}}\]


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