Question

please helppppppppppp

Answer 1

$C=\pi\times d$

for the first one

$\begin{gathered} C=\pi\times4 \\ C=12.56 \end{gathered}$

for the second one

$\begin{gathered} C=(3.14)\times20 \\ C=62.8 \end{gathered}$

and the last one

$\begin{gathered} 28.26=(3.14)\times d \\ \frac{28.26}{3.14}=\frac{3.14\times d}{3.14} \\ d=9 \end{gathered}$