SOLUTION: Two cylinders of equal radii have heights in the ratio of 1:3. If the total surface area of the two cylinders is 770cm2 and the shorter cylinder is 7 cm high, find the common radii

Algebra ->  Surface-area -> SOLUTION: Two cylinders of equal radii have heights in the ratio of 1:3. If the total surface area of the two cylinders is 770cm2 and the shorter cylinder is 7 cm high, find the common radii      Log On


   

Question 1141329: Two cylinders of equal radii have heights in the ratio of 1:3. If the total surface area of the two cylinders is 770cm2 and the shorter cylinder is 7 cm high, find the common radii?

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


small cylinder: radius r, height 7; total surface area 2%28pi%29r%5E2%2B2%28pi%29r%287%29

large cylinder: radius r, height 3*7=21, total surface area 2%28pi%29r%5E2%2B2%28pi%29r%2821%29

The total surface area is 770:

4%28pi%29r%5E2%2B2%28pi%29r%2828%29+=+770

With the "pi"s in that equation, the answer isn't going to be a "nice" number.... Use a calculator....