Mykola V. | Math Tutor - Patient and ExperiencedMath Tutor - Patient and Experienced

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Let's start off with the formula for the area of a circle:

A=πr^{2}. A great way to remember this is to combine it with the circumference formula (C=πd) in a saying that goes like this: Cherry Pie is Delicious, Apple Pies aRe Too.

In any circle we have 360º around. If we know that in 90º the area is 16ft^{2}, and 90 is 1/4 of 360, then we take the 16ft^{2} and multiply it by 4 to get the area of the whole circle.

16*4=64ft^{2}. Now all we do is plug this into the area equation and solve for r.

64=πr^{2} -> 64/π=r^{2} -> √(64/π)=r. Answer. You can now plug that into a calculator to get the definite answer. ^{
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