A hemisphere has a total surface area of 288π cm². Find, correct to one decimal place, its radius

JAMB Mathematics 2023 72 views

A hemisphere has a total surface area of 288π cm². Find, correct to one decimal place, its radius

  1. 9.6 cm
  2. 9.7 cm
  3. 9.8 cm ✓
  4. 9.9 cm

Explanation

Step 1: Write total surface area formula
Total SA = Curved surface + Base
= 2πr² + πr²
= 3πr²

Step 2: Set up equation
3πr² = 288π

Step 3: Divide both sides by π
3r² = 288

Step 4: Solve for r²
r² = 288/3
r² = 96

Step 5: Find radius
r = √96
r = √(16 × 6)
r = 4√6
r ≈ 9.798 cm
r ≈ 9.8 cm (to 1 decimal place)

pastquestions.ng