Short Answer 
The circumference of a circle with a diameter of 20 inches is 20œA inches, and the radius is calculated to be 10 inches. Using this radius, the area of the circle is determined to be 100œA square inches.
Step 1: Understand the Circumference Calculation
The circumference of a circle can be calculated using the formula: Circumference = œA * diameter. In our case, the diameter is given as 20 inches. By substituting the diameter into the formula, we find that the circumference is 20œA inches.
Step 2: Determine the Radius
The radius is essential for calculating the area of the circle. The radius is defined as half of the diameter. Since the diameter is 20 inches, you can compute the radius by using the formula: radius = diameter / 2. This gives us a radius of 10 inches.
Step 3: Calculate the Area
To find the area of the circle, we use the formula: Area = œA * radius¬≤. By substituting the radius of 10 inches into the formula, you perform the calculation as follows: Area = œA * (10)¬≤. Therefore, the area of the circle is 100œA square inches.