posted by Richard on .
The surface area of a cylinder is 200cm. The diameter is equal to the height. Find the radius.
V= πr^2h, but h = r
so V=πr^3 = 200
r^3 = 200/π
r = appr. 4 cm .......(I had 3.9929)
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.
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.