Posted by **Richard** on Sunday, February 20, 2011 at 12:25am.

The surface area of a cylinder is 200cm. The diameter is equal to the height. Find the radius.

- Math -
**Reiny**, Sunday, February 20, 2011 at 1:02am
V= πr^2h, but h = r

so V=πr^3 = 200

r^3 = 200/π

r = appr. 4 cm .......(I had 3.9929)

- Scratch my reply - Math -
**Reiny**, Sunday, February 20, 2011 at 1:05am
Forget this

I read it as volume

Time to go to bed.

SA = 2πr^2 + 2πrh , but h=r

= 2πr^2 + 2πr^2 = 4πr^2

4πr^2 = 200

r^2 = 200/4π

r = 3.989 or appr. 4

Well, what do you know, the answers were the same.

- Math -
**Helper**, Sunday, February 20, 2011 at 9:45am
FYI

Reiny, I didn't see that you had already solved this problem before I answered the same same post below.

I noticed are answers were different.

The height = diameter, not radius.

I am not sure if 'Scratch my reply" means your 1st answer here or your 2nd answer.

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