Answer:
Part A

Plugging in the given values we get;

R = 12 inches
The radius of the circumscribing circle is 12 inches
Part B
The length of each side of the hexagon, 's', is;

Therefore;

s = 12 inches
The perimeter, P = n × s = 6 × 12 = 72 inches
The perimeter of the hexagon is 72 inches
Step-by-step explanation:
The given parameters of the regular hexagon are;
The length of the apothem of the regular hexagon, a = 6·√3 inches
The relationship between the apothem, 'a', and the circumradius, 'R', is given as follows;

Where;
n = The number of sides of the regular polygon = 6 for a hexagon
'a = 6·√3 inches', and 'R' are the apothem and the circumradius respectively;
Part A
Therefore, we have;

Plugging in the values gives;

The circumradius, R = 12 inches
Part B
The length of each side of the hexagon, 's', is given as follows;

Therefore, we get;

The length of each side of the hexagon, s = 12 inches
The perimeter of the hexagon, P = n × s = 6 × 12 = 72 inches
The perimeter of the hexagon = 72 inches