tolong pake cara yaa tolong bantu saya

21) K = 62,8 cm
2×3,14×r = 62,8 cm
6,28× r = 62,8
r = 62,8/6,28
r = 10
Luas = 3,14×10^2
= 3,14×100 cm
314 cm^2


22) Luas bagian diarsir = 1/4×2/3×22/7×10,5^2
= 1/3×11/7×10,5^2
= 1/3×11×15,75
= 57,75 m^2