Answer: 4 units
Step-by-step explanation:
Given : AB is the diameter of a circle.
Then, the central angle for arcADB must be [tex]2\pi[/tex] because the central angle subtended by diameter is [tex]2\pi[/tex] .
The length of arc is given by :-
[tex]L=r\times\theta\\\\\Rightarrow\ 8\pi=r\times2\pi\\\\\Rightarrow\ r=\dfrac{8\pi}{2\pi}=4[/tex]
Hence, the length of the radius of the circle = 4 units
