Area of a square (As) = Side length (L)2
L = square root As
L = square root 49
L = 7 cm
Perimeter (P) = 4L
P = 4 x 7
P = 28 cm
P = Circumference (C)
C = 28 cm
C = 2pi x Radius (r)
r = C / (2pi)
r = 28 / (2pi)
r = 4.45...
r = 4.5 (1 d.p.)