dau coroana ... AC intersectat(cred) BD

a)
P ABCD= 2 L+2l=2 x AB +2 x CD= 2 x 8+2 x 6 = 16+12 =28 cm
b)
AO=OB=OB=OD =5cm
P BOC= BO+OC+BC = 5+5+6= 16 cm