$\text{a)}$   $\text{r}=\frac{6,28}{2\pi }=\frac{6,28}{6,28}=1\text{cm}$

$\text{P}=\pi {\text{r}}^2=\pi {\text{cm}}^2$

 

$\text{b)}$   $\text{r}=\frac{12,56}{2\pi }=\frac{12,56}{6,28}=2\text{m}$

$\text{P}=\pi {\text{r}}^2=4\pi {\text{m}}^2$

 

$\text{c)}$   $\text{r}=\frac{25,12}{2\pi }=\frac{25,12}{6,28}=4\text{mm}$

$\text{P}=\pi {\text{r}}^2=16\pi {\text{mm}}^2$

 

$\text{d)}$ $\text{r}=\frac{60\pi }{2\pi }=30\text{cm}$

$\text{P}=\pi {\text{r}}^2=900\pi {\text{cm}}^2$

 

$\text{e)}$   $\text{r}=\frac{\frac{1}{4}\pi }{2\pi }=\frac{1}{8}\text{dm}$

$\text{P}=\pi {\text{r}}^2=\frac{1}{64}\pi {\text{dm}}^2$

 

$\text{f)}$   $\text{r}=\frac{24\pi }{2\pi }=12\text{m}$

$\text{P}=\pi {\text{r}}^2=144\pi {\text{m}}^2$