square ABCD is divided into 5 equal parts all having same area the central part is circular and the lines AE, GC, BF in HD lie along the diagonals AC and BD of the square if AB is equal to 12 cm find
a)the circumference of the central part
b)the perimeter of the part ABEF

let circle in the middle have radius r
area of circle is (1/5)* area of square of side 22 = (22*22)/5 = 484/5
pi*r^2 = 22*22/5
r^2 = (7/22)*(22*22/5) = 154/5
r^2= 30.8
r = 5.55 cm
cirumference = 2*pi*r = 2*pi*5.55  = 44*5.55/7 = 34.89 cm
AE = BF = (diagnol of square - diameter of circle in the middle)/2
diagonal of square of side 22 cm is
22*sqrt(2) because 22^2 + 22^2 = diagonal^2
AE = BF = (22*sqrt(2) - 2* 5.55 ) /2  = 10 cm
EF is (1/4) circumerence of inner circle  = (1/4) * 34.89 cm
ABFE  perimeter = AB + BF + EF + FE = 22 + 10 + (1/4) * 34.89 + 10 = 50.72 cm