Asked by kelvin

please guys help me this question, how to solve it.

Calculate the total surface area of a hollow cylinder whose radius is 15 cm and height is 20 cm.
Answered by Steve
consider slicing down the side of the cylinder and unrolling the curved part. That is just a rectangle with the same height as the cylinder (h), and a width equal to the circumference (2πr).

So the area is just the inside plus the outside, which are the same, if the cylinder has essentially zero thickness.

A = 2*2πrh
Answered by Henry
As = 2(pi*r^2) + 2pi*r*h = Total surface area.
Convert r and h to meters.
Answered by Henry
Oops! the first term of my Eq does not exist, because the cylinder is hollow.