The area of a circle varies directly as the square of its radius. A circle with radius 2 in. has area 12.568 in. squared. What is the area of a circle with radius 6.2 ​in.?

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Part 1
The area of a circle with radius 6.2 in. is approximately
  
enter your response here
in. squared .
​(Simplify your answer. Round to the nearest thousandth as​ needed.)

1 answer

To find the area of a circle when the radius is given, you can use the formula for the area of a circle:

\[ A = \pi r^2 \]

where \( A \) is the area and \( r \) is the radius.

From the information given, we see that a circle with a radius of 2 inches has an area of 12.568 square inches. Let's check this calculation based on the area formula:

\[ A = \pi (2^2) = \pi (4) \approx 12.566 \text{ square inches} \]

The given area is approximately equal to \( \pi \) (which is about 3.14159); thus the calculation seems consistent.

Now we will find the area for a circle with radius 6.2 inches:

\[ A = \pi (6.2^2) = \pi (38.44) \]

Now, calculate \( \pi \times 38.44 \):

\[ A \approx 3.14159 \times 38.44 \approx 120.655 \]

Rounding to the nearest thousandths, we have:

\[ A \approx 120.655 \text{ in. squared} \]

Thus, the area of a circle with a radius of 6.2 inches is approximately 120.655 in².