Question

What is the radius of the circle?

Answer 1

Using the formula
$\frac{arc}{2 \pi r} = \frac{degree}{360}$

Isolate r
$r= \frac{360arc}{2 \pi degree}$

Insert values and calculate r
$r= \frac{360arc}{2 \pi degree}$ 
$r= \frac{360(8)}{2 \pi 100} m$
$r= \frac{2880)}{200\pi } m$
$r= \frac{14.4}{\pi } m$
$r= 4.563 m$