I think you mean circumference...Area is [tex]A= \pi r^{2} [/tex]. We have the area so we need to use it to solve for the radius which we will then use in the circumference formula. [tex]16 \pi = \pi r^{2} [/tex]. Divide both sides by pi to get [tex] \frac{16 \pi }{ \pi } = r^{2} [/tex]. Of course the simplification of the left side gives us [tex]16= r^{2} [/tex] and r = 4. Now fill that in to the circumference formula, which is [tex]C=2 \pi r[/tex], to get C[tex]C=2 \pi (4)[/tex] which is a circumference of [tex]8 \pi [/tex]
