Multiple choice

If the radius of a sphere is increased by 2 cm. Its surface area increased by 352 cm2. The radius of sphere before change is यदि एक गोले की त्रिज्या में 2 सेमी. की वृद्धि की जाती है | इसका पृष्ठ क्षेत्रफल 352 सेमी.2 से बढ़ जाता है | परिवर्तन से पहले गोले की त्रिज्या है

  1. 3 cm./सेमी.

  2. 4 cm./सेमी.

  3. 5 cm./सेमी.

  4. 6 cm./सेमी.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the original radius be r cm. When increased by 2 cm, new radius is (r+2) cm. Surface area of sphere = 4πr². The increase in surface area is 4π(r+2)² - 4πr² = 352. Solving: 4π(r²+4r+4-r²) = 352 → 4π(4r+4) = 352 → 16π(r+1) = 352 → π(r+1) = 22. Using π = 22/7: r+1 = 7, so r = 6 cm. This matches option D.

Keep practicing — related questions