The radius of a hemisphere is 42 cm. Find half of its curved surface area \(\left(\pi=\frac{22}{7}\right)\).

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SSC GD Constable (2022) Official Paper (Held On : 02 Feb 2023 Shift 4)
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  1. 4554 cm2
  2. 5544 cm2
  3. 3663 cm2
  4. 2772 cm2

Answer (Detailed Solution Below)

Option 2 : 5544 cm2
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Detailed Solution

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Given:

A hemisphere has 42 cm radius.

Concept used:

Curved surface area = 2πr2

The total surface area = 3πr2

Calculations:

According to the question,

Now CSA of hemisphere = 2π(42)2 

Half of CSA = π(42)2

⇒ CSA = (22/7)(1764) 

⇒ CSA = 22 × 252 = 5544 cm2

The answer is 5544 cm2

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