Tolong no 8 & 9 pake caranya?

8.
keliling lingkaran = 2πr
= 2 × 5 × 3,14
= 31,4 cm

keliling bangun = 31,4 + 4 + 4
= 31,4 + 8
= 39,4 cm

9.
keliling = 2πr
6π = 2πr
3 = r

luas = πr²
= π × 3²
= π × 9
= 9π cm²