Circumference of a circle =2πr Area of a circle =πr2 Where r= radius of the circle. But area =64πcm2 πr2=64πcm2 π cancels each other r2=64cm2 64cm2=8cm×8cm 64cm2=(8cm)2 r2=(8cm)2 Since the powers are the same, the bases are also the same. r=8cm Circumference of a circle =2π×8cm Circumference of a circle =16πcm