The internal diameter of a hollow hemispherical vessel is 2.4 cm. It is made of a steel sheet which is 0.5 cm thick. What is the total surface area (in cm2) of the vessel?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is 4 i.e. 612.75π
Explanation :
Internal diameter of hollow hemispherical vessel = 24 cm
Internal radius (r)=24/2=12 cm
External Radius (R)= r + thickness of sheet
= 12 + 0.5 = 12.5 cm
Surface area of internal vessel = 2π × r²=2π × 12² = 288π
Surface area of external vessel = 2π R² = 2π(12.5)² = 312.5
Surface area of ring = π (R² - r²)
= π (12.5² - 12²)
=π (156.25 - 144)
= 12.25π
T.S.A = 288π + 312.5 π + 12.25π
= 612.75π