A hollow hemisphere has an inner radius of 5 cm and an outer radius of 7 cm. Find its total surface area.
Show answer & explanation
Correct answer: B
Explanation
Inner radius = 5 cm
Outer radius = 7 cm
Total surface area of the hollow hemisphere = Outer curved surface area + Inner curved surface area + Annular area of the base
= 2πR² + 2πr² + π(R² − r²)
= 2π(7²) + 2π(5²) + π(7² − 5²)
= 98π + 50π + 24π
= 172π cm²
= 540.57 cm²