# math

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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?

• math -

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.

• math -

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

• math -

don't known

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