Multiple choice

A iron rod is in the form of a square enclosing an area of $22{cm}^{2}$. If the same iron rod is bent into a circle, then find the area of that circle?

  1. $24{cm}^{2}$
  2. $26{cm}^{2}$
  3. $28{cm}^{2}$
  4. $30{cm}^{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A square with area 22 has side length sqrt(22). The perimeter is 4 * sqrt(22). When bent into a circle, the circumference 2 * pi * r = 4 * sqrt(22), so r = 2 * sqrt(22) / pi. Area = pi * r^2 = pi * (4 * 22 / pi^2) = 88 / pi. Using pi approx 3.14, 88 / 3.14 approx 28.02.

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