Point B is between points A and C. If AB = 21 and BC = 33, find AC

We know that
original volume of a cylinder=pi*r²*h
volume=1692.46 in³
1692.46=pi*r²*h

if the radius becomes three times as large
so
r=3*r
new volume=pi*(3*r)²*h> 9*pi*r²*h
new volume=9*original volume
new volume=9*1692.46> 15232.14 in³

the answer is
the new volume is 15232.14 in³