Multiple choice

A solid sphere of diameter 7 cm is cut into two equal halves. What will be the increase (in cm.2) in the total surface area? 7 से.मी. व्यास वाले एक ठोस गोले को दो बराबर भागों में काटा जाता है। कुल पृष्ठीय क्षेत्रफल में कितनी वृद्धि (से.मी.2 में) होगी?

  1. 77

  2. 154

  3. 87

  4. 38.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Original sphere: radius = 3.5 cm, total surface area = 4πr² = 4 × (22/7) × (3.5)² = 154 cm². When cut into two hemispheres, each hemisphere has curved surface area 2πr² and one flat circular face πr². Total for two hemispheres = 2(2πr² + πr²) = 6πr² = 308 cm². Increase = 308 - 154 = 154 cm². Option B is correct.

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