math
posted by priya on .
A cylinder has a diameter of 80 cm and a length of 45 cm. Another cylinder has the same volume but is 80cm long. What is the diameter of the longer cylinder?

Volume of cylinder
= πr²h
= π(80/2)²*45
= 72000π
Volume of the other cylinder = 72000π
= π(diameter/2)²*80
Solve for diameter in
72000π = π (diameter/2)²*80
I get diameter=60. 
V=([d^2*pi)/4] *L
[(80^2*pi)/4]*45=[(d^2*pi)/4]*(45+80)
Multipy both sides of this equation with(4/pi)
(80^2)*45=d^2*(45+80)
6400*45=d^2*125
288000=d^2*125
Divide both sides with 125
288000/125=d^2
2304=d^2
d=sqroot(2304)
d=48 cm 
don't known