Question

22. Two concentric circles with Centre O have A,B,C and D as points of intersection with a line l as
shown in the figure. If AD=12 cm and BC = 8 cm, find the lengths of AB and CD.
Dal
C
B
AL​

Answer 1

Since, OM ⊥ BC

BM = CM = ½ BC = 4 cm



Also     OM ⊥ AD

So     AM = DM = ½ AD = 6  cm

Now     AB = AM – BM = (6 – 4) cm = 2 cm

CD = DM – CM = ( 6 – 4) cm = 2 cm

∴    AC = AB + BC = (2 + 8) cm = 10 cm

and   BD = BC + CD = (8 + 2)cm = 10 cm.