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What is the approximate area of a circle with a diameter of 18 in?

OA. 56.5 in²
OB. 28.3 in2
OC. 254 in²
OD. 1018 in²

1 Answer

5 votes

Area of a circle:
\pi r^2

We need to find the radius of the circle before we can find the area. The radius of a circle is half of the diameter. We are already given the diameter, so the radius would be 1/2d, where d = diameter.

Plug in 18 for d
\implies (1)/(2) (18) = 9.

The radius of this circle is 9 inches. Now we can plug in 9 for r in the formula for area of a circle.


\pi 9^2 = 254.34 (rounded to the nearest whole)

The area of the circle is 254 in².

User Bob Cross
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