tolong dijawab pake cara no 9 dan 10

9. r= 21:2
10,5
L=22/7x10,5x10,5
=22x1,5x10,5
=346,5m²

10 1,54x100=154
154=22/7x r²
r²=49
r=7dm---> r=70cm

1,54 x 100 = 154 cm
154 x 7/22 = 49
√49 = 7 x 2 = 14 cm

22/7 x 21 x 21 = 1.386 m