As we can see, the radius of the circle is 3r and the side length of the square is 2( 3r)= 6r. Using these values we can evaluate our ratio. Let's recall that the area of the circle is the product of pi and the squared radius, and the area of the square is the squared side length.
A_c/A_s=π ( 3r)^2/( 6r)^2
Now we will simplify the ratio. We will start with distributing the powers to the terms in parentheses.