2021 · Q77
Consider the following for the next three (03) items that follow : A solid consisting of a right circular cone of radius x and height 2x standing on a hemisphere of radius x (take π = 22/7). What is the approximate total surface area of the solid ?
Elementary MathematicsMensuration
- A11.2x²
- B12.5x²
- C13.3x²
- D15.1x²
Explanation
The cone's slant height is √(x² + 4x²) = x√5. Total surface area = cone CSA + hemisphere CSA = πx·x√5 + 2πx² = π(√5+2)x² ≈ (22/7)(4.236)x² ≈ 13.35x². The nearest option is (c) 13.3x².