SOLUTION: for a scietific experiment, Tony needs a glass bell jar in the shape of a cylinder with a hemispere on top. The height of the cylinder must be 3 inches longer that its radius and t

Question 546281: for a scietific experiment, Tony needs a glass bell jar in the shape of a cylinder with a hemispere on top. The height of the cylinder must be 3 inches longer that its radius and the volume must be 72 pie cubic inches. What should the radius of the cylinder be?
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
for a scietific experiment, Tony needs a glass bell jar in the shape of a cylinder with a hemispere on top. The height of the cylinder must be 3 inches longer that its radius and the volume must be 72 pie cubic inches. What should the radius of the cylinder be?
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let r=radius
volume of hemisphere=(1/2)(4/3)πr^3=(2/3)πr^3
volume of cylinder=πr^2*height=πr^2(r+3)
volume of hemisphere+volume of cylinder=72π
(2/3)πr^3+πr^2(r+3)=72π
divide by π
(2/3)r^3+r^2(r+3)=72
(2/3)r^3+r^3+3r^2=72
(5/3)r^3+3r^2-72=0
5r^3+9r^2-216=0
I don't know how to solve this cubic equation, but my computer graphics program gave an answer of radius=3
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