Curved surface area of a hemisphere, diameter 28 cm:\nFind the curved surface area (in cm²).

Difficulty: Easy

Correct Answer: 1232

Explanation:


Introduction / Context:
The curved surface area (CSA) of a hemisphere depends only on the radius via CSA = 2πr^2.



Given Data / Assumptions:

  • Diameter = 28 cm ⇒ r = 14 cm.


Concept / Approach:
Apply CSA = 2πr^2 directly and evaluate numerically.



Step-by-Step Solution:

1) CSA = 2 * π * 14^2 = 2 * π * 196 = 392π.2) Using π ≈ 22/7 ⇒ CSA = 392 * 22/7 = 56 * 22 = 1232 cm².


Verification / Alternative check:
Using π ≈ 3.1416 gives ≈ 1231.5, which rounds to 1232.


Why Other Options Are Wrong:
1152, 1024, 956 do not equal 392π.


Common Pitfalls:
Using sphere area 4πr^2 or including the base area; only curved area is asked.


Final Answer:
1232.

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