A) 364.5
B) 346.5
C) 693.5
D) 639.5
Correct Answer: B
$ \therefore $ $ \frac{\sqrt{3}}{4}a^{2}=121\sqrt{3} $
$ \Rightarrow $ $ a^{2}=121\times 4 $
$ \Rightarrow $ $ a=11\times 2=22cm $
$ \therefore $ Perimeter of triangle $ =3\times 22=66cm $
$ \Rightarrow $ Circumference of circle = Perimeter of equilateral triangle
$ \Rightarrow $ $ 2\pi r=66 $
$ \Rightarrow $ $ r=\frac{66\times 7}{2\times 22}=\frac{21}{2}=10.5 $ Hence, area of circle $ =\pi (r^{2}) $ $ =\frac{22}{7}\times {{(10.5)}^{2}}=346.5cm^{2} $