Mathematics
An open hollow cylindrical container, made of very thin metal sheet, has radius r cm and height h cm, its total surface area (in cm2) is :
πr2h + 2πrh
4πrh + πr2
4πrh + 2πr2
2πrh + 2πr2
Answer
Given,
It is an open hollow cylindrical container.
∴ It will be open at one end and closed at the other end.
Since, hollow cylindrical container is made up of very thin metal sheet.
∴ External radius = Internal radius = r cm.
Given,
Height = h cm.
Total surface area of hollow cylinder = External curved surface area + Internal curved surface area + Area of cross section (lower end)
= 2πrh + 2πrh + πr2
= 4πrh + πr2.
Hence, Option 2 is the correct option.
Related Questions
The curved area of a solid cylinder is S cm2 and the circumference of its base is C cm; the height of the cylinder is :
C × S
C + S
S ÷ C
S - C
The total surface area of an open pipe of length H cm, external radius R cm and internal radius r cm, is :
πR2 - πr2 + 2π(R - r)H
2πR2 - 2πr2 + 2πRH
2πRH - 2πrh + πR2 - πr2
2(πR2 - πr2) + 2πRH + 2πrH