tolong ya...1 sampe 4 pake cara.yg cepat d like

1)r=d/2=21/2=10,5
v=3,14×10,5^2×24=8.308,44
2)d=r×2=28×2=56
v=3,14×56^2×18=177.246,72
3)r=196/2=98
v=3,14×98^2×60=1.809.393,6
4)r=21/2=10,5
t=3.465/3,14×10,5^2=3.465/346,185=99,845