How to find radius ????

Dear Student

1 . if the diameter is given the radius will be half of the diameter.
 For example: if the diameter is 10 cm then the radius will be half of it =5cm
diameter, d =10cm
radius r= $\frac{d}{2} =\frac{10}{2} =5cm$ 



2. if the circumference is given we should divide the circumference by 2 $\mathrm{\pi }$
For example:  - if the circumference. is 44 cm the radius r =
 

circumference = 2 r
$$\begin{gathered} 44 =2\mathrm{\pi r} \\ \mathrm{r} =\frac{44}{2\mathrm{\pi }} \\ \mathrm{\pi } =\frac{22}{7} \mathrm{or} 3.14 \\ \mathrm{r} =\frac{44}{2\times {\displaystyle \frac{22}{7}}} \\ \mathrm{r} = 7 \mathrm{cm} \end{gathered}$$

Regards