The formula for the area of a circle is: A = π r²
If you use 3.14 for π, the formula would be:
A = 3.14 x 9²
A = 3.14 x 81
A = 254.34 square inches
The answer will vary depending upon what is used for pi. An online calculator for the area of a circle gives an answer of 254.469.
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If the diameter of a circle is 18 inches then its radius is 18/2 = 9 inches
The formula for area of a circle is: A = (pi)*r^2 If the diameter of a circle is 6 then the circle's radius is 3. So, A = (pi)*(3)^2 A= 9*(pi) inches squared or A = 28.26 inches squared (rounded)
Since your circle has a diameter of 9 feet (the definition of a "9 by 9" circle), the radius is half of that distance. In this case, your radius is 4.5 feet or 54 inches.
The area of a circle with a diameter of 9 inches is: 63.62 square inches.
Radius = Diameter/2. So in this case 4.5 inches.