Question 1038277
We know that the area of a circle is defined as {{{A = pi * r^2}}}.
Since we already have the area, and need to determine the radius, we just use a little algebra. 

{{{A/pi = r^2}}}

{{{sqrt(A/pi) = r}}},  since we know that the radius is positive, we do not need to take the positive and negative of r, only the positive. So the radius is...

{{{sqrt(400)/sqrt(pi) = r}}}

and then...

{{{(20/(sqrt(pi))) = r}}}

Approximately 11.3 rounded to the tenths

And the circumference of the floor is {{{2*pi*r}}}

which is {{{2*pi*(20/(sqrt(pi)))}}}

so...

{{{40*pi/(sqrt(pi))}}}

which is approximately 70.9 rounded to the tenth

I hope this helps! Learn on