Step 1

The picture below shows the circle with the radius r.

Step 2

To find the radius of a circle, we can start with the formula for the area of a circle:

Step 3

Since the value of the area is given as 314 in², we can substitute A with 314. Similarly, we can substitute π with 3.14. These are shown below: 

Step 4

Now, we have 3.14r² = 314. To get closer in finding r, we need to remove 3.14. To do so, we divide both sides of the equation with 3.14 as shown below:

Step 5

Now, we have r² = 100. Since r square is a multiplication of r two times, we can find r by taking the square root of 100. This is shown below:

Step 6

Now, the calculated number 10, has no meaning unless we include the unit for it. Since the area is in in², r will be in inch. Hence:

r = 10 in

Step 7

Therefore, the answer is D.

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