Abaikan no. 11, bantu dong no. 10 dan 12

10. sudut AOB/sudut COD=l.juring AOB/l.juring COD
63/42=15/l.juring COD
21/14=15/l.juring COD
7/14=5/l.juring COD
1/2=5/l.juring COD
l.juring COD=5×2=10cm2(B)

12. AC kuadrat=OA kuadrat-OC kuadrat
=10 kuadrat-6 kuadrat
=100-36=64
AC=akar kuadrat 64=8cm(B)