The area of a circle is 314.2 square feet. What s the length of it's radius?

$$Area = \pi r^2\\

314.2=\pi\times r^2\\

314.2 \div\pi =r^2\\

r^2\approx 100\\

r\:\:\approx 10feet$$

10 ft pi r^2

OK

A = pi * r^2

So

314.2 = pi * r^2     Divide both sides by pi

314.2 / pi = r^2      Take the square root of both sides

√(314.2 / pi)   = r   = 10.00064829093329474 ft  or about 10 ft