FRAC{\pi {{d}^{2}}}{
4
}=154\Rightarrow d=\
SQRT
{\frac{154\times 4}{\pi }}=\sqrt{\frac{154\times 4\times
7
}{22}}\] \[=\sqrt{{{2}^{2}}\times {{7}^{2}}}2\times 7=14\,\,cm\]