Curved surface area of a hemisphere — diameter given: Find the curved surface area (CSA) of a hemisphere of diameter 28 cm.

Introduction / Context:The curved surface area of a hemisphere equals 2πr^2. With a diameter given, first compute the radius and then evaluate the expression, preferably using π = 22/7 for exact integer results with multiples of 7.

Given Data / Assumptions:

• Diameter = 28 cm ⇒ r = 14 cm.
• CSA (hemisphere) = 2πr^2.

Concept / Approach:Substitute r into 2πr^2 and simplify exactly.

Step-by-Step Solution:CSA = 2π * 14^2 = 2π * 196 = 392πWith π = 22/7: 392π = 392 * 22/7 = 56 * 22 = 1232 cm2

Verification / Alternative check:Using π ≈ 3.1416 gives ≈ 1231.5 cm2, rounding to the nearest integer 1232.

Why Other Options Are Wrong:1236, 1238, 1233 are near but not equal to the exact evaluation.

Common Pitfalls:Confusing hemisphere CSA (2πr^2) with total surface area (3πr^2).

Final Answer:1232 sq cm