The internal and external radius of a hollow hemispherical vessel are 7 cm and 8 cm respectively. What is total surface area of the vessel?
Answer & explanation
Correct answer: option 4
T.S.A. = C.S.A. of (inner + outer) hemispherical + area of ring
= 2\(\pi \) (R2 + r2) + \(\pi \) (R2 - r2)
= 3\(\pi \) R2 + \(\pi \) r2
= \(\pi \) (3 × (8)2 + (7)2)
= 3.14 × 241 = 756.74 cm2