The area of the square is 16 cm². What is the length of one side? The
circles inside the square are all the
same size. What is a radius of one
circle? What is the area of one circle?

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.