If the area of a circle is 16pi what is the circumference of the circle, circle b, if its radius is 1/2 that of the circle a

First find the radius of circle A. You know that the equation is r^2*pi, so just divide both by pi.

r^2*pi=16pi

/pi / pi

r^2=16

R is 4. That means that circle B is 2, since its radius is half that of circle A.

C=pi2r

C=pi2 (2)

C=pi4

C=4pi

The answer is 4pi.