The total surface area of a closed hemisphere is 4158 cm². What is the diameter of the hemisphere? [Use π = 22/7]
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Correct answer: D
Explanation
The correct answer is option 4 i.e. 42 cm
total surface area of a closed hemisphere = 3π × (radius)2
4158 = 3 × 22/7 × (radius)2
63 = 1/7 × (radius)2
7 × 9 × 7 = (radius)²
(7 × 3)2 = (radius)2
radius = 21 cm
diameter of the hemisphere = 2 × radius
= 2 × 21
= 42cm