Find the surface area (in cm2) of a sphere whose diameter is 21 cm.
Show answer & explanation
Correct answer: C
Explanation
The correct answer is Option 3 i.e. 1386.
Diameter = 21 cm → Radius = 21 ÷ 2 = 10.5 cm
Surface area of sphere = 4 × π × r²
= 4 × 3.14 × (10.5)²
= 4 × 3.14 × 110.25 ≈ 1385.64 cm² ≈ 1386 cm2