Question

the total surface area of hollow cylinder of internal radius r and height h is​

Answer 1

Step-by-step explanation:

A hollow cylinder is made up of two thin sheets of rectangle having a length and breadth. Also, the radius of both the cylinders can be r1+r2. Therefore, the surface area of the cylinder is equal to the surface area of both the rectangles which is equal to 2π( r1 + r2)( r1 – r2 +h).