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If R and r denote the external and internal radii of a hollow right circular cylinder respectively and h is the height, then the total surface area becomes
1. 2π(R+r)(R+h-r)
2. 2π(R+r)(R+h)
3. 2π(R+r)
4. 10π(R+r)

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Correct Answer - Option 1 : 2π(R+r)(R+h-r)

Given:

Height = h, R = external radius and r = internal radius

Formula:

Total surface area of cylinder = lateral surface area + area of bases

Calculation:

Lateral surface area of hollow cylinder = 2πh(R + r)

Area of bases = 2π(R2 - r2)

Total surface area of hollow cylinder = 

⇒ 2πh(R + r) + 2π(R2 - r2)

⇒ 2πh(R + r) + 2π(R + r)(R - r)

⇒ 2π(R + r)(h + R - r)

⇒ 2π(R + r)(R + h - r)

∴ Total surface area of hollow cylinder = 2π(R + r)(R + h - r)

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