please jawab,bsk di kumpul

18.
Kling = 1/2 3,14 x d
Kling = 1/2 3,14 x 20
Kling = 10 x 3,14
Kling = 31,4

Keliling = 30 + 31,4 + 30 + 31,4
= 122,8 (A)

19.
K1 = 3/4 x 22/7 x 14 = 33

K2 = 2 x 1/4 x 22/7 x 14 = 22

Keliling = K1 + K2
= 33 + 22
= 55 (A)

20.
K = 3/4 x 3,14 x 20
K = 47,1 ( D)

#maaf, no 17 sy ga paham