Multiple choice

The area of a circle is increased by 22 cm its radius is increased by 1 cm. The original radius of The circle is -

  1. 3.2 cm

  2. 3.5 cm

  3. 3 cm

  4. 6 cm
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Original area = πr². New area = π(r+1)² = π(r² + 2r + 1). Increase = π(2r + 1) = 22. So 2r + 1 = 22/π ≈ 7, giving r ≈ 3. Using π ≈ 22/7: 2r + 1 = 22/(22/7) = 7, so 2r = 6, r = 3 cm. Checking: Original area = 9π ≈ 28.3, new area = 16π ≈ 50.3, difference = 7π ≈ 22 ✓

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