Answer:
9.9
Explanation:
To solve this problem, we first need to know that the whole length of the circunference is related to a central angle of 2pi radians. Then, we can solve using a rule of three to find the radius:
arc of 6.6 -> central angle of 2/3
arc of 2*pi*r -> central angle of 2pi
2*pi*r * (2/3) = 6.6 * 2*pi
r * (2/3) = 6.6
r = 6.6 / (2/3) = 9.9
So the length of the radius is 9.9