Explanation
Each tube has a diameter of 3. The circumference of any of the circles (including A) \(=\pi d\) (where d = diameter). Given a diameter of 3, the circumference of circle \(A=3 \pi\).
There is enough information since there is a value to 3 pi which is approximately 9.42 or you can keep it as 3 pi to have an exact answer.