Answer:
See below.
Explanation:
We are asked for the diameter, radius, and area of a circle.
We are given the Circumference.
We should know that;

(Exact)
This means that the Diameter is 24.
The Radius is
of the Diameter.
This means that the Radius is 12.
The area of a circle is represented as;

We have the requirements to find the area, with the value of the radius.
Solve for the area;

(Exact)
(Approx.)