Answer:
9 and 18
Step-by-step explanation:

The first one is rectangle
Answer: 4
Step-by-step explanation:
There are 4 terms, 
The axis of symmetry of a parabola in the form

is a vertical line

where k is the x coordinate of the vertex of the parabola.
The x coordinate of the vertex of the parabola is given by

which in your case is

So, the axis of symmetry is the line x=12.
The radius is always half the diameter. So, your answer is A.