Answer:
r = [tex]\frac{84.78}{2 \pi}\\[/tex] ≈ 13.493 mm
Step-by-step explanation:
The formula for the circumference c of a circle is
[tex]c = 2 * \pi * r[/tex] ,
where r is the radius.
Dividing both sides of the equation gives
[tex]\frac{c}{2 \pi} = r[/tex].
Plugging in c = 84.78 gives you the Answer.
