9)

a =5/18 *360° =100°

l =5/18 C (???)

10)

∠KOL=60, △KOL -р/б с углом 60° - равносторонний, KL=OK=R

C =2пR => 8√3п =2пR => R=4√3 =KL

13)

C =2пR => C =24п

∪KL =1/6 C =4п

14)

l/C =72°/360° => l =30п/5 =6п