no 30,31,32 caranya gimana

30.
[tex] \frac{22}{7} \times 3.5 \times 3.5 = \frac{22}{7} \times 12.25 \\ \frac{269.5}{7} = 38.5 \\ [/tex]
jari²=3. 5 diameter=B. 7

31.keliling=31. 4 diameter=10 cm
luas=3. 14x5x5
= 3.14x25
=B. 78,5 cm