bantu jawab no.19&20 ya makasih

19. Lp bola = 4πr²
154 =4×22/7
r²=154×7/88
r²=12,25
r=√12,55=3,5
v bola=4/3πr³
4/3×22/7×3,5×3,5×3,5
539/3
=179,67cm³
20.
r=4cm
t=9cm
d=20cm
∆vt=vk
πrt²×∆t=1/3πrk²tk
rt²×∆t=1/3rk²tk
5²×∆t=1/3×4×4×9
25×∆t=48
∆t=48/25=1,92cm