## anonymous 5 years ago i have a cylinder with a volume of 603.1857895, and surface area is 351.8583772, i need to find the radius and the height

1. anonymous

Volume of a cylinder = (pi) * r^2 = 603.1857895 Surface Area of a Cylinder = 2(pi) * r^2 + 2(pi) * r * h = 351.8583772 is that good?

2. anonymous

ops, typo. Volume of a cylinder = (pi) * r^2 * h = 603.1857895 Surface Area of a Cylinder = 2(pi) * r^2 + 2(pi) * r * h = 351.8583772 two unknowns and two equations

3. anonymous

no, i already new that don't know where to go from there

4. anonymous

r(1)=0.103 r(2(=56,3

5. anonymous

i am trying to build a cylinder and all i have is the surface area and the volume, nothing else, i have been working on this for hours and very frustrated. i have found many places that show me the formulas but none that actually show you how to do it backwards

6. anonymous

$Volume = (\pi)r^2h = 603.1857895$$Surface = 2(\pi)r^2 + 2(\pi)rh = 351.8583772$ from volume equation:$h = {603.1857895 \over \pi r^2}$ substitute in the surface eqt.:$2 \pi r^2 + 2 \pi r ({603.1857895 \over \pi r^2}) = 351.8583772$$2 \pi r^2 + {2*603.1857895 \over r} = 351.8583772$ solve for r and then solve for h

7. anonymous

does that hlep?

8. anonymous

the actual paper i have has it written as 192 times pi, for the volume, and 112 times pi for the surface area, my teacher sucks and doesn't use 3.14 for pi, would this make this equation any easier

9. anonymous

it is a lot easier if yu just use the symbol (pi) instead of the actual number because at the end it is most likely to be canceled..

10. anonymous

for example, when i found H. If you had just left as the (pi) symbol:$h={603.1857895 \over \pi r^2} = { 192 \pi \over \pi r^2} = { 192 \over r^2}$ See ?

11. anonymous

yes thank you

12. anonymous

now it just made everything much easier. Can yu solve from now on?

13. anonymous

i think so