C. 12π cm
Feedback Let the radii of the larger and the smaller circles be l cm and s cm respectively. Let the side of the square be a cm.
a^2 = 784 = (4)(196) = (2^2).(14^2)
a = (2)(14) = 28
a = 2l, l = a/2 = 14
l = (7/3)s
Therefore s = (3/7)(l) = 6 Circumference of the smaller circle = 2∏s = 12∏ cm.